{"gene":"PF3D7_0202000","run_date":"2026-09-07T10:55:51","timeline":{"discoveries":[{"year":1997,"finding":"Targeted gene disruption of KAHRP demonstrated it is essential for knob formation on P. falciparum-infected erythrocytes; knob-negative transfectants showed dramatically reduced binding to CD36 under flow conditions mimicking postcapillary venules, establishing that knobs are required for cytoadherence under physiological shear stress.","method":"Targeted gene disruption (knockout), flow-based adhesion assay, static adhesion assay","journal":"Cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean gene knockout with specific phenotypic readout (knob loss, reduced flow adhesion), replicated in multiple assay formats, highly cited foundational study","pmids":["9108483"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2001,"finding":"GFP fusions and FRAP experiments demonstrated that KAHRP is trafficked from the parasite endomembrane system through an intermediate depot (Maurer's clefts) between parasite and host, then into the erythrocyte cytoplasm and finally into knobs; sequence elements in KAHRP were identified as essential for individual steps in this pathway, establishing Maurer's clefts as an elaboration of the secretory pathway transposed outside the parasite.","method":"GFP fusion constructs, live fluorescence microscopy, FRAP (fluorescence recovery after photobleaching), domain deletion analysis","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (GFP chimeras, FRAP, domain mutants) in a single rigorous study with specific pathway placement","pmids":["11598007"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2002,"finding":"Micropipette aspiration of infected RBCs from KAHRP-knockout parasites showed KAHRP contributes approximately 51% of the overall increase in membrane shear elastic modulus (rigidity) that occurs in P. falciparum-infected RBCs, a significantly greater contribution than PfEMP3 (~15%).","method":"Micropipette aspiration, gene knockout (kahrp deletion), quantitative biophysics","journal":"Blood","confidence":"High","confidence_rationale":"Tier 2 / Strong — quantitative biophysical assay on clean knockout parasites, specific phenotypic readout with defined magnitude","pmids":["11807013"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":1999,"finding":"Direct binding experiments showed KAHRP interacts with the cytoplasmic domain of PfEMP1 (VARC); three KAHRP fragments were identified that bind VARC, with two high-affinity binding regions mapping to the 63-residue histidine-rich region and the 70-residue 5' repeat region of KAHRP (Kd ~10^-7 M and ~3.3×10^-6 M respectively); deletion of both regions abolished VARC binding.","method":"In vitro binding assay (recombinant protein fragments), binding affinity measurements, deletion mutagenesis","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro binding reconstitution with quantitative Kd measurements and deletion mutagenesis confirming specific binding domains","pmids":["10446142"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2005,"finding":"The binding site for spectrin on KAHRP was mapped to a 72-amino-acid fragment (residues 370–441), and the reciprocal KAHRP-binding site on spectrin was localized to repeat 4 of alpha-spectrin (alpha N-5 fragment); resealing of the repeat 4 peptide into erythrocytes mislocalised KAHRP in parasitized cells, establishing that the KAHRP–spectrin interaction is critical for correct membrane localization of KAHRP.","method":"In vitro binding assay (recombinant fragments), competition assay, erythrocyte resealing experiment, immunofluorescence","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — in vitro domain mapping combined with functional erythrocyte resealing experiment showing in-cell consequence, multiple orthogonal methods","pmids":["16006556"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2006,"finding":"Expression of mutant KAHRP constructs in transgenic P. falciparum showed that the C-terminal repeat region of KAHRP is critical for formation of functional knobs (assessed by atomic force and electron microscopy); the 5' repeat region of KAHRP is important for cross-linking to the host-cell cytoskeleton, required for knob protrusion and efficient adhesion under physiological flow conditions.","method":"Stable transgenic parasite lines expressing KAHRP domain mutants, atomic force microscopy, electron microscopy, flow adhesion assay","journal":"Blood","confidence":"High","confidence_rationale":"Tier 2 / Strong — domain-specific mutants in live parasites with multiple structural and functional readouts","pmids":["16507777"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2000,"finding":"In vitro binding experiments demonstrated that the cytoplasmic domain of PfEMP1 (VAR_CD) binds to full-length KAHRP with an apparent Kd of ~10.7 nM; KAHRP polypeptides self-associate in solution to form knob-like structures and show binding to spectrin-actin-protein 4.1 complexes; VAR_CD also binds F-actin (Kd ~44.9 nM) and spectrin.","method":"In vitro binding assay, affinity measurements, self-association assay, co-sedimentation","journal":"Molecular and biochemical parasitology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — quantitative in vitro reconstitution showing KAHRP self-association and binding to host cytoskeletal components with Kd values, single lab","pmids":["10838226"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2013,"finding":"KAHRP, but not PfEMP1, PfEMP3, or RESA, binds to erythrocyte ankyrin R; the KAHRP binding site on ankyrin R was mapped to the D3 subdomain of the 89 kDa membrane-binding domain, and the ankyrin-binding segment on KAHRP was localized to a 79-residue sequence; loading erythrocytes with soluble D3 subdomain prevented KAHRP from migrating to the host cell membrane, leaving it diffusely distributed in the cytosol.","method":"In vitro binding assay, domain mapping, erythrocyte resealing/loading experiment, immunofluorescence","journal":"Biochimica et biophysica acta","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — in vitro domain mapping combined with functional erythrocyte loading experiment showing in-cell localization consequence, multiple orthogonal methods","pmids":["24090929"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":1986,"finding":"Isolation of cDNA clones for KAHRP showed that in knobless mutants of P. falciparum the KAHRP gene has undergone a chromosomal rearrangement resulting in a deletion in the 3' coding sequence and a telomeric relocation of the truncated gene on chromosome 2, explaining loss of KAHRP mRNA and protein expression and knobless phenotype.","method":"cDNA cloning, Southern blotting, chromosomal mapping","journal":"Nature","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct molecular characterization linking gene deletion to protein loss and phenotype, single lab with clear genetic evidence","pmids":["3016553"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":1987,"finding":"The complete gene sequence of KAHRP was determined; the gene contains a single intron at the 3' boundary of the signal peptide hydrophobic core; the protein contains a histidine-rich region and two separate repeat blocks (5' repeats related to SKKHKDNEDAESVK, and 3' repeats related to SKGATKEAST), both of which bear epitopes recognized by human antibodies during natural infection.","method":"cDNA and chromosomal clone sequencing, E. coli expression of repeat domains, human antibody reactivity assay","journal":"The EMBO journal","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — complete gene/protein sequence with functional validation of repeat domain immunogenicity, single foundational study","pmids":["3301325"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":1987,"finding":"Immunoelectron microscopy using affinity-purified antibodies against recombinant KAHRP established that the protein is clustered on the cytoplasmic side of the erythrocyte membrane and is physically associated with the electron-dense knobs.","method":"Immunoelectron microscopy, indirect immunofluorescence, recombinant protein expression in E. coli","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct subcellular localization by immunoelectron microscopy with monospecific antibodies, single lab","pmids":["3313387"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":1992,"finding":"Stage-specific nuclear run-on analysis demonstrated that KAHRP gene transcription is developmentally regulated during the intraerythrocytic cycle; a sequence motif with two-fold symmetry located 160 bp upstream of the RNA initiation site interacts with parasite nuclear extracts in a stage-specific manner correlating with transcriptional activity of the KAHRP gene.","method":"Nuclear run-on analysis, protein-DNA interaction assay (gel shift/footprinting), genomic sequence analysis","journal":"Nucleic acids research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct transcription assay plus protein-DNA interaction showing stage-specific regulation, single lab with two methods","pmids":["1620601"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2005,"finding":"The N-terminal protein export element (signal/PEXEL region) of KAHRP, when appended to the transmembrane and C-terminal domains of PfEMP1, was sufficient for efficient trafficking of those domains to the outside of the P. falciparum-infected RBC membrane; the physical state of exported proteins suggested trafficking as a complex rather than in vesicles.","method":"GFP chimera constructs, fluorescence microscopy, FRAP","journal":"Blood","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — chimeric construct trafficking experiment with FRAP, single lab, two methods","pmids":["15692070"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2016,"finding":"A mutated KAHRP construct with the PEXEL motif repositioned near the signal sequence was not cleaved by plasmepsin V and was not exported, despite retaining putative PI(3)P-binding residues; restoring the PEXEL to its original position restored processing by plasmepsin V and export, demonstrating that PEXEL position is conserved for co-translational processing and export.","method":"Site-directed mutagenesis of KAHRP PEXEL motif, transfection, export assay, biochemical processing analysis","journal":"Nature communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — mutant construct in live parasites with specific biochemical and export readout, single lab","pmids":["26832821"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2009,"finding":"In vitro binding assays showed that VARC phosphorylation by erythrocytic casein kinase II (CKII) alters the binding of VARC to KAHRP; inhibition of CKII reduced cytoadherence of infected RBCs to ICAM-1 and CSA, suggesting KAHRP–VARC interaction is modulated by CKII-mediated phosphorylation.","method":"In vitro binding assay, CKII inhibitor/enhancer treatment, phosphorylation assay, cytoadherence assay","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vitro and in vivo evidence for phosphorylation-dependent modulation of KAHRP–VARC interaction, single lab","pmids":["19131328"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2015,"finding":"Electron tomography of detergent-insoluble skeletons from P. falciparum 3D7 schizonts revealed a highly organized knob skeleton comprising a spiral structure coated by an electron-dense layer; immuno-EM localized KAHRP within these structures, and connections from the knob skeleton to the erythrocyte cytoskeleton were observed.","method":"Electron tomography, immuno-electron microscopy, freeze-fracture scanning EM","journal":"Blood","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct structural localization of KAHRP by immuno-EM within tomographic context, single lab, multiple EM methods","pmids":["26637786"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":"3D7"}]},{"year":2017,"finding":"Biophysical and structural analyses showed that a repeat region in KAHRP preferentially associates with domains 10–14 of β-spectrin (proximal to the spectrin-ankyrin complex), while the PfEMP1 cytosolic domain interacts broadly with spectrin but shows preference for domain 17 of α-spectrin; structural models combined with prior data suggested a model for knob architecture.","method":"Biophysical binding assays, structural analysis, computational modeling","journal":"PLoS pathogens","confidence":"Medium","confidence_rationale":"Tier 1–2 / Moderate — biophysical domain mapping with structural and computational validation, single lab","pmids":["28806784"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2019,"finding":"Correlative STORM-SEM showed KAHRP is delivered as individual modules that assemble in situ at the RBC membrane skeleton, giving a ring-shaped fluorescence profile around a dimpled disk visible by SEM; electron tomography revealed a spiral scaffold underlying assembled knobs; truncation of the KAHRP C-terminal region caused loss of ring structures, disruption of raised disks, and aberrant spiral scaffold formation; host cell actin remodeling (blocked by cytochalasin D) was required for knob assembly.","method":"Correlative STORM-SEM, electron tomography, KAHRP C-terminal truncation mutants, cytochalasin D treatment, super-resolution microscopy","journal":"PLoS pathogens","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal high-resolution imaging methods with domain truncation and pharmacological perturbation, defining assembly mechanism","pmids":["31071194"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2021,"finding":"Super-resolution microscopy (single-molecule localization) showed KAHRP initially associates with ankyrin bridges in the erythrocyte skeleton but eventually colocalizes with remnant actin junctions; a 35 Å cryo-EM map of the spiral scaffold underlying knobs was obtained and a KAHRP-targeting nanoprobe was shown to bind close to the spiral; approximately 60 KAHRP molecules per knob were detected.","method":"Super-resolution single-molecule localization microscopy (SMLM), cryo-electron microscopy, KAHRP nanoprobe, quantitative fluorescence analysis","journal":"Molecular microbiology","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — cryo-EM structure combined with super-resolution localization and quantification, multiple orthogonal methods in single study","pmids":["34514656"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2015,"finding":"Dynamic NMR and binding assays identified four positively charged linear sequence motifs of high intrinsic mobility in KAHRP that interact electrostatically with VARC (cytoplasmic domain of PfEMP1) in solution to form a 'fuzzy complex'; co-localization of KAHRP and VARC to membrane knobs was confirmed by immunofluorescence.","method":"NMR spectroscopy, in vitro binding assay, immunofluorescence co-localization","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 1 / Moderate — NMR-based structural characterization of interaction motifs combined with co-localization, single lab","pmids":["25726759"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2012,"finding":"Co-immunoprecipitation assays demonstrated that KAHRP is in a complex with the parasite Hsp40 (KAHsp40/PF3D7_0201800), PfEMP3, and Hsp101; double IFA showed co-localization of KAHsp40 with KAHRP at the erythrocyte periphery in structures consistent with knobs.","method":"Co-immunoprecipitation, immunofluorescence assay (IFA), subcellular fractionation","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — co-IP identifying complex membership, supported by co-localization; single lab, does not establish KAHRP's own mechanistic role beyond complex membership","pmids":["22970262"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2002,"finding":"Flow-based adhesion assay using KAHRP-knockout parasite lines showed that loss of KAHRP had a significant effect on the ability of parasitized RBCs to adhere under flow conditions, comparable in impact to loss of PfEMP3 but distinct from loss of RESA or MESA.","method":"Competitive flow-based adhesion assay, gene-knockout parasite lines","journal":"British journal of haematology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean knockout with quantitative flow adhesion assay, single lab","pmids":["11918556"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2005,"finding":"PfTBP (TATA-binding protein) was shown by supershift, footprinting, and chromatin immunoprecipitation assays to associate in vivo with a consensus TATA box sequence located 81 bp upstream of the KAHRP transcription start site, identifying a functional cis-acting element and its trans-acting factor for KAHRP promoter regulation.","method":"Supershift assay, DNase I footprinting, chromatin immunoprecipitation (ChIP)","journal":"Molecular and biochemical parasitology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods (footprinting, supershift, ChIP) establishing promoter mechanism, single lab","pmids":["15760658"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":1994,"finding":"Mapping of endonuclease hypersensitive sites in P. falciparum chromatin revealed that spontaneous chromosome breakages within the KAHRP gene coding region occur preferentially within linker regions of nucleosomes with a periodicity of ~155 bp, corresponding to the P. falciparum nucleosome repeat unit, establishing that chromatin structure determines the sites of chromosome breakage.","method":"Mapping of endonuclease hypersensitive sites, nucleosome periodicity analysis, pulsed-field gel electrophoresis","journal":"Nucleic acids research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct chromatin structure mapping at KAHRP locus showing mechanistic basis for breakage, single lab","pmids":["8065922"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2010,"finding":"In P. berghei, a GFP construct bearing a KAHRP-like N-terminus (signal sequence + PEXEL/VTS motif) was exported into the erythrocyte cytosol, whereas a construct with a PfEMP1-like N-terminus (lacking signal sequence before PEXEL) was not, suggesting proteins with KAHRP-like architecture follow a distinct common export pathway.","method":"GFP reporter constructs, P. berghei transfection, fluorescence microscopy","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional export assay using KAHRP signal architecture in a heterologous Plasmodium system, single lab","pmids":["20419102"],"is_preprint":false,"attribution":[{"species":"Plasmodium berghei","strain":""}]},{"year":2003,"finding":"Confocal microscopy and FRAP showed that erythrocytes infected with a KAHRP-null parasite strain exhibit the same decrease in lateral mobility of host membrane proteins (band 3, glycophorin) as wild-type infected erythrocytes, indicating KAHRP does not contribute to immobilization of host membrane proteins.","method":"Confocal microscopy, FRAP, KAHRP-null parasite line","journal":"Blood","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — clean knockout with specific functional readout, but this is a negative result (KAHRP not involved in host protein immobilization)","pmids":["14615371"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]}],"current_model":"KAHRP (PF3D7_0202000) is an exported P. falciparum protein that is essential for knob formation on infected erythrocytes: it is trafficked from the parasite endomembrane system via Maurer's clefts to the cytoplasmic face of the erythrocyte membrane, where it self-assembles into ring-shaped structures (~60 molecules/knob) that form a spiral scaffold anchored to the host spectrin-actin cytoskeleton through direct interactions with α-spectrin repeat 4 (via a 72-residue KAHRP fragment) and ankyrin R (via a 79-residue KAHRP segment); KAHRP's 5' repeat region cross-links to the cytoskeleton to drive knob protrusion, while its C-terminal repeat region is critical for functional knob formation; KAHRP also directly binds the cytoplasmic domain of PfEMP1 (VARC) through its histidine-rich and 5' repeat regions, an interaction modulated by erythrocytic casein kinase II phosphorylation of VARC; together, these interactions account for ~51% of the increased membrane rigidity of infected RBCs and are required for cytoadherence under physiological flow conditions."},"narrative":{"mechanistic_narrative":"KAHRP (PF3D7_0202000) is an exported P. falciparum protein essential for assembling knobs on the surface of infected erythrocytes, structures required for cytoadherence of parasitized red cells under physiological shear stress [PMID:9108483]. Following co-translational PEXEL processing by plasmepsin V, whose motif position is essential for export [PMID:26832821], KAHRP is trafficked from the parasite endomembrane system through Maurer's clefts into the erythrocyte cytoplasm and finally into knobs, with distinct sequence elements governing individual steps of this pathway [PMID:11598007]. At the cytoplasmic face of the host membrane KAHRP self-associates into knob-like structures [PMID:10838226] and assembles in situ as individual modules into ring-shaped units (~60 molecules per knob) that build a spiral scaffold [PMID:31071194, PMID:34514656]. This scaffold is anchored to the host spectrin-actin cytoskeleton through direct, domain-mapped interactions: a 72-residue KAHRP fragment binds repeat 4 of α-spectrin [PMID:16006556], a 79-residue segment binds the D3 subdomain of ankyrin R [PMID:24090929], and disrupting either interaction mislocalizes KAHRP to the cytosol, establishing that cytoskeletal attachment governs correct membrane targeting [PMID:16006556, PMID:24090929]. KAHRP also directly binds the cytoplasmic domain of PfEMP1 (VARC) with high affinity through its histidine-rich and 5' repeat regions [PMID:10446142, PMID:10838226], forming an electrostatic 'fuzzy complex' [PMID:25726759] whose strength is modulated by erythrocytic casein kinase II phosphorylation of VARC [PMID:19131328]. Functionally, the 5' repeat region cross-links to the cytoskeleton to drive knob protrusion and adhesion, while the C-terminal repeat region is critical for functional knob formation and spiral scaffold integrity [PMID:16507777, PMID:31071194]; collectively these interactions account for roughly 51% of the increased membrane rigidity of infected red cells [PMID:11807013]. KAHRP does not contribute to immobilization of host membrane proteins, indicating its mechanical role is confined to knob assembly [PMID:14615371].","teleology":[{"year":1986,"claim":"Establishing the molecular basis of the knobless phenotype linked KAHRP gene integrity to knob formation, showing that loss of KAHRP expression underlies the knobless state.","evidence":"cDNA cloning, Southern blotting, and chromosomal mapping in knobless P. falciparum mutants","pmids":["3016553"],"confidence":"Medium","gaps":["Correlational: gene rearrangement linked to phenotype without direct functional rescue","Did not define KAHRP molecular function"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":1987,"claim":"Sequencing and immunolocalization defined KAHRP's domain architecture and placed the protein physically at knobs, providing the structural foundation for later mechanistic dissection.","evidence":"Gene/protein sequencing plus immunoelectron microscopy with recombinant-protein antibodies","pmids":["3301325","3313387"],"confidence":"Medium","gaps":["Function of the histidine-rich and repeat domains not yet tested","No binding partners identified"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":1997,"claim":"Targeted disruption resolved whether KAHRP is merely a knob component or is required for the adhesion phenotype, demonstrating it is essential for knob formation and flow-based cytoadherence.","evidence":"Gene knockout with static and flow-based CD36 adhesion assays","pmids":["9108483"],"confidence":"High","gaps":["Did not identify the molecular interactions underlying knob assembly","Contribution to membrane mechanics not quantified"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2000,"claim":"In vitro reconstitution addressed how KAHRP bridges the parasite adhesin to the host skeleton, showing high-affinity binding to the PfEMP1 cytoplasmic domain, self-association into knob-like structures, and binding to spectrin-actin-4.1 complexes.","evidence":"In vitro binding, affinity measurements, self-association and co-sedimentation assays","pmids":["10838226","10446142"],"confidence":"High","gaps":["In-cell relevance of the mapped binding regions not yet tested","Reciprocal binding sites on host proteins not defined"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2001,"claim":"Live-cell trafficking analysis defined the export route of KAHRP, placing Maurer's clefts as an intermediate depot and mapping sequence elements to individual trafficking steps.","evidence":"GFP fusions, live microscopy, FRAP, and domain deletion analysis","pmids":["11598007"],"confidence":"High","gaps":["Molecular machinery mediating each step not identified","PEXEL processing requirement not yet resolved"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2002,"claim":"Quantitative biophysics answered how much KAHRP contributes to the mechanical stiffening of infected cells, showing it accounts for ~51% of the increased membrane shear modulus.","evidence":"Micropipette aspiration of KAHRP-knockout versus wild-type infected RBCs; competitive flow adhesion assays","pmids":["11807013","11918556"],"confidence":"High","gaps":["Which molecular interactions produce the rigidity increase not resolved by this assay"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2005,"claim":"Domain mapping and in-cell perturbation defined KAHRP's spectrin anchor and its export signal, showing the α-spectrin repeat 4 interaction is required for correct membrane localization and that the N-terminal export element can traffic heterologous cargo.","evidence":"Recombinant fragment binding, erythrocyte resealing of competing peptide, immunofluorescence, and GFP chimera trafficking","pmids":["16006556","15692070"],"confidence":"High","gaps":["Additional cytoskeletal anchors not yet identified","Whether spectrin binding drives knob mechanics untested"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2006,"claim":"Domain-specific transgenic mutants assigned functions to KAHRP's repeat regions, showing the 5' repeats mediate cytoskeletal cross-linking and protrusion while the C-terminal repeats are required for functional knob formation.","evidence":"Transgenic parasites expressing KAHRP domain mutants analyzed by atomic force microscopy, electron microscopy, and flow adhesion","pmids":["16507777"],"confidence":"High","gaps":["Structural basis of C-terminal repeat function not defined","Molecular partner of the C-terminal region unknown"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2009,"claim":"Identifying casein kinase II modulation showed the KAHRP-PfEMP1 interaction is regulated by host-cell phosphorylation, linking a signaling input to cytoadherence.","evidence":"In vitro binding with CKII treatment, phosphorylation assay, and cytoadherence to ICAM-1/CSA","pmids":["19131328"],"confidence":"Medium","gaps":["Physiological trigger controlling CKII activity not defined","Effect on knob architecture not measured"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2013,"claim":"Discovery of the ankyrin R interaction defined a second, KAHRP-specific host anchor required for membrane targeting, distinguishing KAHRP from other exported proteins.","evidence":"In vitro binding, domain mapping to ankyrin D3 subdomain, and erythrocyte D3-loading with immunofluorescence","pmids":["24090929"],"confidence":"High","gaps":["Relative contributions of spectrin versus ankyrin binding to assembly not resolved","Order of anchor engagement during assembly untested at this stage"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2015,"claim":"Structural and complex analyses refined the KAHRP-PfEMP1 interaction and placed KAHRP in a knob-associated protein complex, describing an electrostatic fuzzy complex and membership with Hsp40, PfEMP3 and Hsp101.","evidence":"NMR of KAHRP-VARC binding motifs, immunofluorescence co-localization, electron tomography, and co-immunoprecipitation","pmids":["25726759","26637786","22970262"],"confidence":"Medium","gaps":["Co-IP establishes complex membership but not KAHRP's specific role within it","Stoichiometry and dynamics of the fuzzy complex in vivo unknown"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2017,"claim":"Preferential spectrin sub-domain mapping refined the architectural model, showing KAHRP repeats associate with β-spectrin domains near the spectrin-ankyrin junction distinct from PfEMP1's preferred α-spectrin site.","evidence":"Biophysical binding assays with structural analysis and computational modeling","pmids":["28806784"],"confidence":"Medium","gaps":["Model not validated by high-resolution structure of the assembled interface"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2019,"claim":"High-resolution correlative imaging resolved how KAHRP assembles into knobs, showing in-situ modular assembly into rings over a spiral scaffold that depends on the C-terminal region and host actin remodeling.","evidence":"Correlative STORM-SEM, electron tomography, C-terminal truncation mutants, and cytochalasin D treatment","pmids":["31071194"],"confidence":"High","gaps":["Molecular trigger initiating spiral nucleation not defined","Role of actin junction remodeling relative to spectrin/ankyrin anchoring unresolved"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2021,"claim":"Cryo-EM and single-molecule localization quantified knob composition and captured a shift in KAHRP's host anchoring during assembly, from ankyrin bridges to remnant actin junctions, with ~60 KAHRP molecules per knob.","evidence":"Single-molecule localization microscopy, 35 Å cryo-EM of the spiral scaffold, and a KAHRP-targeting nanoprobe","pmids":["34514656"],"confidence":"High","gaps":["Atomic-resolution structure of KAHRP within the scaffold not yet achieved","Mechanism driving the ankyrin-to-actin transition unknown"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":null,"claim":"A high-resolution molecular structure of KAHRP within the assembled spiral scaffold, and the mechanism controlling ordered engagement of its multiple host anchors during knob nucleation, remain unresolved.","evidence":"","pmids":[],"confidence":"High","gaps":["No atomic-resolution structure of KAHRP in situ","Order and regulation of spectrin, ankyrin, and actin engagement during assembly not fully defined","How PfEMP1 loading is coordinated with scaffold maturation unknown"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]}],"mechanism_profile":{"molecular_activity":[],"localization":[],"pathway":[],"complexes":["Knob spiral scaffold (~60 KAHRP molecules per knob)","KAHRP–PfEMP1(VARC) fuzzy complex","KAHRP–α-spectrin repeat 4 complex","KAHRP–ankyrin R (D3 subdomain) complex","KAHRP / KAHsp40 (PF3D7_0201800) / PfEMP3 / Hsp101 complex"],"partners":["PFEMP1 CYTOPLASMIC DOMAIN (VARC/VAR_CD)","ERYTHROCYTE Α-SPECTRIN (REPEAT 4)","ERYTHROCYTE Β-SPECTRIN (DOMAINS 10–14)","ERYTHROCYTE ANKYRIN R (D3 SUBDOMAIN)","SPECTRIN-ACTIN-PROTEIN 4.1 COMPLEX / F-ACTIN","KAHSP40 (PF3D7_0201800)","PFEMP3","HSP101","PLASMEPSIN V (PEXEL PROCESSING)","ERYTHROCYTIC CASEIN KINASE II (VIA VARC PHOSPHORYLATION)"],"other_free_text":["KAHRP contains a signal peptide with a single intron at the 3' boundary of its hydrophobic core, a histidine-rich region, a 5' repeat block (SKKHKDNEDAESVK-related) and a 3' repeat block (SKGATKEAST-related); both repeat blocks carry epitopes recognized by human infection antibodies [#9].","Export requires a correctly positioned PEXEL motif for plasmepsin V co-translational processing [#13].","KAHRP transcription is stage-specific during the intraerythrocytic cycle, regulated via an upstream two-fold-symmetric motif and a TATA box bound by PfTBP [#11, #22].","In knobless mutants a chromosomal rearrangement deletes the 3' coding sequence and relocates a truncated KAHRP gene, abolishing expression [#8]; chromosome breakage within the coding region occurs preferentially at nucleosome linker regions [#23].","KAHRP does not contribute to immobilization of host membrane proteins band 3 and glycophorin [#25].","In P. berghei, a KAHRP-like N-terminal architecture (signal sequence plus PEXEL/VTS) is sufficient for export into the erythrocyte cytosol, unlike a PfEMP1-like N-terminus [#24]."]}},"prefetch_data":{},"corpus_meta":[{"pmid":"11598007","id":"PMC_11598007","title":"Trafficking and assembly of the cytoadherence complex in Plasmodium falciparum-infected human erythrocytes.","date":"2001","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/11598007","citation_count":400,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP","knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"1979090","id":"PMC_1979090","title":"Human cerebral malaria: association with erythrocyte rosetting and lack of anti-rosetting antibodies.","date":"1990","source":"Lancet (London, England)","url":"https://pubmed.ncbi.nlm.nih.gov/1979090","citation_count":380,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"9108483","id":"PMC_9108483","title":"Targeted gene disruption shows that knobs enable malaria-infected red cells to cytoadhere under physiological shear stress.","date":"1997","source":"Cell","url":"https://pubmed.ncbi.nlm.nih.gov/9108483","citation_count":366,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP","knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"11807013","id":"PMC_11807013","title":"Contribution of parasite proteins to altered mechanical properties of malaria-infected red blood cells.","date":"2002","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/11807013","citation_count":188,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP","knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"25108687","id":"PMC_25108687","title":"Efficient CRISPR-Cas9-mediated genome editing in Plasmodium falciparum.","date":"2014","source":"Nature methods","url":"https://pubmed.ncbi.nlm.nih.gov/25108687","citation_count":182,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP","knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"6208311","id":"PMC_6208311","title":"Knob-positive and knob-negative Plasmodium falciparum differ in expression of a strain-specific malarial antigen on the surface of infected erythrocytes.","date":"1984","source":"The Journal of experimental medicine","url":"https://pubmed.ncbi.nlm.nih.gov/6208311","citation_count":172,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"7630387","id":"PMC_7630387","title":"Natural selection on Plasmodium surface proteins.","date":"1995","source":"Molecular and biochemical parasitology","url":"https://pubmed.ncbi.nlm.nih.gov/7630387","citation_count":163,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP","knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"3016553","id":"PMC_3016553","title":"A chromosomal rearrangement in a P. falciparum histidine-rich protein gene is associated with the knobless phenotype.","date":"1986","source":"Nature","url":"https://pubmed.ncbi.nlm.nih.gov/3016553","citation_count":161,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP","knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"16507777","id":"PMC_16507777","title":"The role of KAHRP domains in knob formation and cytoadherence of P falciparum-infected human erythrocytes.","date":"2006","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/16507777","citation_count":126,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP","knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"10446142","id":"PMC_10446142","title":"Mapping the binding domains involved in the interaction between the Plasmodium falciparum knob-associated histidine-rich protein (KAHRP) and the cytoadherence ligand P. falciparum erythrocyte membrane protein 1 (PfEMP1).","date":"1999","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/10446142","citation_count":117,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP","knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"15692070","id":"PMC_15692070","title":"Trafficking of the major virulence factor to the surface of transfected P. falciparum-infected erythrocytes.","date":"2005","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/15692070","citation_count":114,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP","knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"2648403","id":"PMC_2648403","title":"Subtelomeric chromosome deletions in field isolates of Plasmodium falciparum and their relationship to loss of cytoadherence in vitro.","date":"1989","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/2648403","citation_count":114,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP","knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"10838226","id":"PMC_10838226","title":"Plasmodium falciparum erythrocyte membrane protein 1 is anchored to the actin-spectrin junction and knob-associated histidine-rich protein in the erythrocyte skeleton.","date":"2000","source":"Molecular and biochemical parasitology","url":"https://pubmed.ncbi.nlm.nih.gov/10838226","citation_count":112,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP","knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"16006556","id":"PMC_16006556","title":"Structural and functional studies of interaction between Plasmodium falciparum knob-associated histidine-rich protein (KAHRP) and erythrocyte spectrin.","date":"2005","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/16006556","citation_count":84,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP","knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"3301325","id":"PMC_3301325","title":"The complete sequence of the gene for the knob-associated histidine-rich protein from Plasmodium falciparum.","date":"1987","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/3301325","citation_count":84,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP","knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"3313387","id":"PMC_3313387","title":"Primary structure and subcellular localization of the knob-associated histidine-rich protein of Plasmodium falciparum.","date":"1987","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/3313387","citation_count":81,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"2666153","id":"PMC_2666153","title":"Plasmodium falciparum: cytoadherence of a knobless clone.","date":"1989","source":"Experimental parasitology","url":"https://pubmed.ncbi.nlm.nih.gov/2666153","citation_count":62,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP","knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"14668007","id":"PMC_14668007","title":"Common trafficking pathway for variant antigens destined for the surface of the Plasmodium falciparum-infected erythrocyte.","date":"2004","source":"Molecular and biochemical parasitology","url":"https://pubmed.ncbi.nlm.nih.gov/14668007","citation_count":58,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP","knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"26832821","id":"PMC_26832821","title":"Export of malaria proteins requires co-translational processing of the PEXEL motif independent of phosphatidylinositol-3-phosphate binding.","date":"2016","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/26832821","citation_count":57,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"1620601","id":"PMC_1620601","title":"A sequence element associated with the Plasmodium falciparum KAHRP gene is the site of developmentally regulated protein-DNA interactions.","date":"1992","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/1620601","citation_count":56,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP","knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"22249178","id":"PMC_22249178","title":"Structural analysis of the Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) intracellular domain reveals a conserved interaction epitope.","date":"2012","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/22249178","citation_count":52,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP","knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"12095684","id":"PMC_12095684","title":"Analysis of transcriptomes of human malaria parasite Plasmodium falciparum using full-length enriched library: identification of novel genes and diverse transcription start sites of messenger RNAs.","date":"2002","source":"Gene","url":"https://pubmed.ncbi.nlm.nih.gov/12095684","citation_count":49,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"26637786","id":"PMC_26637786","title":"A spiral scaffold underlies cytoadherent knobs in Plasmodium falciparum-infected erythrocytes.","date":"2015","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/26637786","citation_count":43,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP","knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"11755194","id":"PMC_11755194","title":"Mapping the domains of the cytoadherence ligand Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) that bind to the knob-associated histidine-rich protein (KAHRP).","date":"2002","source":"Molecular and biochemical parasitology","url":"https://pubmed.ncbi.nlm.nih.gov/11755194","citation_count":43,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP","knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"19131328","id":"PMC_19131328","title":"Erythrocytic casein kinase II regulates cytoadherence of Plasmodium falciparum-infected red blood cells.","date":"2009","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/19131328","citation_count":41,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP","knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"16262789","id":"PMC_16262789","title":"Trafficking determinants for PfEMP3 export and assembly under the Plasmodium falciparum-infected red blood cell membrane.","date":"2005","source":"Molecular microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/16262789","citation_count":40,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP","knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"1944415","id":"PMC_1944415","title":"In vivo and in vitro derived Palo Alto lines of Plasmodium falciparum are genetically unrelated.","date":"1991","source":"Molecular and biochemical parasitology","url":"https://pubmed.ncbi.nlm.nih.gov/1944415","citation_count":39,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"22970262","id":"PMC_22970262","title":"An exported heat shock protein 40 associates with pathogenesis-related knobs in Plasmodium falciparum infected erythrocytes.","date":"2012","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/22970262","citation_count":38,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"11918556","id":"PMC_11918556","title":"Assignment of functional roles to parasite proteins in malaria-infected red blood cells by competitive flow-based adhesion assay.","date":"2002","source":"British journal of haematology","url":"https://pubmed.ncbi.nlm.nih.gov/11918556","citation_count":38,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP","knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"8065922","id":"PMC_8065922","title":"Chromatin structure determines the sites of chromosome breakages in Plasmodium falciparum.","date":"1994","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/8065922","citation_count":38,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"15780346","id":"PMC_15780346","title":"Distribution of Plasmodium falciparum genotypes in clinically mild and severe malaria cases in Orissa, India.","date":"2005","source":"Transactions of the Royal Society of Tropical Medicine and Hygiene","url":"https://pubmed.ncbi.nlm.nih.gov/15780346","citation_count":37,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP","knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"24090929","id":"PMC_24090929","title":"Interaction of Plasmodium falciparum knob-associated histidine-rich protein (KAHRP) with erythrocyte ankyrin R is required for its attachment to the erythrocyte membrane.","date":"2013","source":"Biochimica et biophysica acta","url":"https://pubmed.ncbi.nlm.nih.gov/24090929","citation_count":36,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP","knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"21696460","id":"PMC_21696460","title":"Genetic ablation of a Maurer's cleft protein prevents assembly of the Plasmodium falciparum virulence complex.","date":"2011","source":"Molecular microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/21696460","citation_count":34,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP","knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"15760658","id":"PMC_15760658","title":"Recombinant and native Plasmodium falciparum TATA-binding-protein binds to a specific TATA box element in promoter regions.","date":"2005","source":"Molecular and biochemical parasitology","url":"https://pubmed.ncbi.nlm.nih.gov/15760658","citation_count":32,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"25850860","id":"PMC_25850860","title":"The Plasmodium falciparum exportome contains non-canonical PEXEL/HT proteins.","date":"2015","source":"Molecular microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/25850860","citation_count":31,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"28806784","id":"PMC_28806784","title":"Structural analysis of P. falciparum KAHRP and PfEMP1 complexes with host erythrocyte spectrin suggests a model for cytoadherent knob protrusions.","date":"2017","source":"PLoS pathogens","url":"https://pubmed.ncbi.nlm.nih.gov/28806784","citation_count":30,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP","knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"1773882","id":"PMC_1773882","title":"Knobs, knob proteins and cytoadherence in falciparum malaria.","date":"1991","source":"The International journal of biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/1773882","citation_count":27,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"11071296","id":"PMC_11071296","title":"The cytoadherence ligand Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) binds to the P. falciparum knob-associated histidine-rich protein (KAHRP) by electrostatic interactions.","date":"2000","source":"Molecular and biochemical parasitology","url":"https://pubmed.ncbi.nlm.nih.gov/11071296","citation_count":26,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP","knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"8303938","id":"PMC_8303938","title":"Immunogenicity and antigenicity of a Plasmodium falciparum protein fraction (90-110 kDa) able to protect squirrel monkeys against asexual blood stages.","date":"1994","source":"Vaccine","url":"https://pubmed.ncbi.nlm.nih.gov/8303938","citation_count":26,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"2448620","id":"PMC_2448620","title":"Structure and expression of the knob-associated histidine-rich protein of Plasmodium falciparum.","date":"1987","source":"Molecular and biochemical parasitology","url":"https://pubmed.ncbi.nlm.nih.gov/2448620","citation_count":26,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"14615371","id":"PMC_14615371","title":"Plasmodium falciparum induces reorganization of host membrane proteins during intraerythrocytic growth.","date":"2003","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/14615371","citation_count":26,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"26443460","id":"PMC_26443460","title":"Plasmodium falciparum-infected erythrocyte knob density is linked to the PfEMP1 variant expressed.","date":"2015","source":"mBio","url":"https://pubmed.ncbi.nlm.nih.gov/26443460","citation_count":25,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP","knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"9107533","id":"PMC_9107533","title":"Erythrocyte membrane alterations in Plasmodium falciparum malaria sequestration.","date":"1997","source":"Current opinion in hematology","url":"https://pubmed.ncbi.nlm.nih.gov/9107533","citation_count":25,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"10838219","id":"PMC_10838219","title":"Plasmodium falciparum: red blood cell binding studies of peptides derived from histidine-rich KAHRP-I, HRP-II and HRP-III proteins.","date":"2000","source":"Acta tropica","url":"https://pubmed.ncbi.nlm.nih.gov/10838219","citation_count":23,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"31071194","id":"PMC_31071194","title":"The knob protein KAHRP assembles into a ring-shaped structure that underpins virulence complex assembly.","date":"2019","source":"PLoS pathogens","url":"https://pubmed.ncbi.nlm.nih.gov/31071194","citation_count":23,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP","knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"3286310","id":"PMC_3286310","title":"Genomic organization, structure and possible function of histidine-rich proteins of malaria parasites.","date":"1988","source":"The International journal of biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/3286310","citation_count":21,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP","knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"7937144","id":"PMC_7937144","title":"Transcriptional and nucleosomal characterization of a subtelomeric gene cluster flanking a site of chromosomal rearrangements in Plasmodium falciparum.","date":"1994","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/7937144","citation_count":21,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"25726759","id":"PMC_25726759","title":"Dynamic association of PfEMP1 and KAHRP in knobs mediates cytoadherence during Plasmodium invasion.","date":"2015","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/25726759","citation_count":20,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP","knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"34614006","id":"PMC_34614006","title":"Co-chaperone involvement in knob biogenesis implicates host-derived chaperones in malaria virulence.","date":"2021","source":"PLoS pathogens","url":"https://pubmed.ncbi.nlm.nih.gov/34614006","citation_count":20,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"26304012","id":"PMC_26304012","title":"A repeat sequence domain of the ring-exported protein-1 of Plasmodium falciparum controls export machinery architecture and virulence protein trafficking.","date":"2015","source":"Molecular microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/26304012","citation_count":20,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"37505649","id":"PMC_37505649","title":"Knobs, Adhesion, and Severe Falciparum Malaria.","date":"2023","source":"Tropical medicine and infectious disease","url":"https://pubmed.ncbi.nlm.nih.gov/37505649","citation_count":16,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"8603725","id":"PMC_8603725","title":"Allelic forms of the knob associated histidine-rich protein gene of Plasmodium falciparum.","date":"1996","source":"FEBS letters","url":"https://pubmed.ncbi.nlm.nih.gov/8603725","citation_count":16,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP","knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"20419102","id":"PMC_20419102","title":"Functional evaluation of Plasmodium export signals in Plasmodium berghei suggests multiple modes of protein export.","date":"2010","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/20419102","citation_count":15,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP","knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"28981210","id":"PMC_28981210","title":"Proteome and Structural Organization of the Knob Complex on the Surface of the Plasmodium Infected Red Blood Cell.","date":"2017","source":"Proteomics. Clinical applications","url":"https://pubmed.ncbi.nlm.nih.gov/28981210","citation_count":15,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"1673101","id":"PMC_1673101","title":"Plasmodium falciparum: genetic stability of the Uganda Palo Alto strain propagated in the squirrel monkey (Saimiri sciureus).","date":"1991","source":"Experimental parasitology","url":"https://pubmed.ncbi.nlm.nih.gov/1673101","citation_count":15,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"25342752","id":"PMC_25342752","title":"Targeted disruption of a ring-infected erythrocyte surface antigen (RESA)-like export protein gene in Plasmodium falciparum confers stable chondroitin 4-sulfate cytoadherence capacity.","date":"2014","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/25342752","citation_count":13,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"9128177","id":"PMC_9128177","title":"Variations in the C-terminal repeats of the knob-associated histidine-rich protein of Plasmodium falciparum.","date":"1997","source":"Biochimica et biophysica acta","url":"https://pubmed.ncbi.nlm.nih.gov/9128177","citation_count":13,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP","knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"27382019","id":"PMC_27382019","title":"Infectivity of Plasmodium falciparum in Malaria-Naive Individuals Is Related to Knob Expression and Cytoadherence of the Parasite.","date":"2016","source":"Infection and immunity","url":"https://pubmed.ncbi.nlm.nih.gov/27382019","citation_count":13,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"34514656","id":"PMC_34514656","title":"KAHRP dynamically relocalizes to remodeled actin junctions and associates with knob spirals in Plasmodium falciparum-infected erythrocytes.","date":"2021","source":"Molecular microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/34514656","citation_count":12,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP","knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"9291676","id":"PMC_9291676","title":"Knob proteins in falciparum malaria.","date":"1997","source":"The Indian journal of medical research","url":"https://pubmed.ncbi.nlm.nih.gov/9291676","citation_count":12,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP","knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"3053455","id":"PMC_3053455","title":"Expression of the histidine-rich protein PfHRP1 by knob-positive Plasmodium falciparum is not sufficient for cytoadherence of infected erythrocytes.","date":"1988","source":"Infection and immunity","url":"https://pubmed.ncbi.nlm.nih.gov/3053455","citation_count":11,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"34802442","id":"PMC_34802442","title":"Safety, infectivity and immunogenicity of a genetically attenuated blood-stage malaria vaccine.","date":"2021","source":"BMC medicine","url":"https://pubmed.ncbi.nlm.nih.gov/34802442","citation_count":10,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP","knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"30081913","id":"PMC_30081913","title":"A bioreactor system for the manufacture of a genetically modified Plasmodium falciparum blood stage malaria cell bank for use in a clinical trial.","date":"2018","source":"Malaria journal","url":"https://pubmed.ncbi.nlm.nih.gov/30081913","citation_count":10,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP","knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"21860664","id":"PMC_21860664","title":"Tetracysteine-based fluorescent tags to study protein localization and trafficking in Plasmodium falciparum-infected erythrocytes.","date":"2011","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/21860664","citation_count":9,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP","knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"33202000","id":"PMC_33202000","title":"A proteomic glimpse into the effect of antimalarial drugs on Plasmodium falciparum proteome towards highlighting possible therapeutic targets.","date":"2021","source":"Pathogens and disease","url":"https://pubmed.ncbi.nlm.nih.gov/33202000","citation_count":9,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"35394995","id":"PMC_35394995","title":"A particle-based computational model to analyse remodelling of the red blood cell cytoskeleton during malaria infections.","date":"2022","source":"PLoS computational biology","url":"https://pubmed.ncbi.nlm.nih.gov/35394995","citation_count":8,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP","knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"3550477","id":"PMC_3550477","title":"Knob-associated histidine-rich protein gene.","date":"1987","source":"Nature","url":"https://pubmed.ncbi.nlm.nih.gov/3550477","citation_count":6,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"21594767","id":"PMC_21594767","title":"Genetic polymorphism at the C-terminal domain (region III) of knob-associated histidine-rich protein (KAHRP) of Plasmodium falciparum in isolates from Iran.","date":"2011","source":"Parasitology research","url":"https://pubmed.ncbi.nlm.nih.gov/21594767","citation_count":4,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP","knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"3279953","id":"PMC_3279953","title":"Viruslike particles containing knob-associated histidine-rich protein are secreted into the culture medium of Plasmodium falciparum in vitro cultures.","date":"1988","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/3279953","citation_count":4,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"40077967","id":"PMC_40077967","title":"Pair cross-correlation analysis for assessing protein co-localization.","date":"2025","source":"Biophysical journal","url":"https://pubmed.ncbi.nlm.nih.gov/40077967","citation_count":2,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"30279439","id":"PMC_30279439","title":"Genetic conflicts with Plasmodium parasites and functional constraints shape the evolution of erythrocyte cytoskeletal proteins.","date":"2018","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/30279439","citation_count":1,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"30191063","id":"PMC_30191063","title":"Genetic diversity at the C-terminal domain of knob-associated histidine-rich protein (KAHRP) of Plasmodium falciparum isolates from Burundi, Eastern Africa.","date":"2018","source":"Annals of medicine and surgery (2012)","url":"https://pubmed.ncbi.nlm.nih.gov/30191063","citation_count":1,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP","knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"40133663","id":"PMC_40133663","title":"Deep learning image analysis for continuous single-cell imaging of dynamic processes in Plasmodium falciparum-infected erythrocytes.","date":"2025","source":"Communications biology","url":"https://pubmed.ncbi.nlm.nih.gov/40133663","citation_count":1,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP","knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"35387278","id":"PMC_35387278","title":"Genetic Diversity, Repeat Motifs, and Natural Selection at the C-Terminal Knob-Associated Histidine Rich Protein (KAHRP) of Plasmodium falciparum Clinical Samples from Saudi Arabia.","date":"2022","source":"Journal of tropical medicine","url":"https://pubmed.ncbi.nlm.nih.gov/35387278","citation_count":0,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP","knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"39829786","id":"PMC_39829786","title":"Nucleotide-resolution Mapping of RNA N6-Methyladenosine (m6A) modifications and comprehensive analysis of global polyadenylation events in mRNA 3' end processing in malaria pathogen Plasmodium falciparum.","date":"2025","source":"bioRxiv : the preprint server for biology","url":"https://pubmed.ncbi.nlm.nih.gov/39829786","citation_count":0,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["KAHRP"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"10831395","id":"PMC_10831395","title":"Plasmodium falciparum: polymorphism in regions II and III of the knob-associated histidine-rich protein gene from two areas of different endemicity.","date":"2000","source":"Experimental parasitology","url":"https://pubmed.ncbi.nlm.nih.gov/10831395","citation_count":0,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["knob-associated histidine-rich protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":35905,"output_tokens":6928,"usd":0.105817,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":14525,"output_tokens":5901,"usd":0.110075,"stage2_stop_reason":"end_turn"},"total_usd":0.215892,"stage1_batch_id":"msgbatch_01DbiymDmubkPpYvdbAu5a7V","stage2_batch_id":"msgbatch_012TbrWvMRH129T7PQ4SmvrJ","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1997,\n      \"finding\": \"Targeted gene disruption of KAHRP demonstrated it is essential for knob formation on P. falciparum-infected erythrocytes; knob-negative transfectants showed dramatically reduced binding to CD36 under flow conditions mimicking postcapillary venules, establishing that knobs are required for cytoadherence under physiological shear stress.\",\n      \"method\": \"Targeted gene disruption (knockout), flow-based adhesion assay, static adhesion assay\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean gene knockout with specific phenotypic readout (knob loss, reduced flow adhesion), replicated in multiple assay formats, highly cited foundational study\",\n      \"pmids\": [\"9108483\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"GFP fusions and FRAP experiments demonstrated that KAHRP is trafficked from the parasite endomembrane system through an intermediate depot (Maurer's clefts) between parasite and host, then into the erythrocyte cytoplasm and finally into knobs; sequence elements in KAHRP were identified as essential for individual steps in this pathway, establishing Maurer's clefts as an elaboration of the secretory pathway transposed outside the parasite.\",\n      \"method\": \"GFP fusion constructs, live fluorescence microscopy, FRAP (fluorescence recovery after photobleaching), domain deletion analysis\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (GFP chimeras, FRAP, domain mutants) in a single rigorous study with specific pathway placement\",\n      \"pmids\": [\"11598007\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Micropipette aspiration of infected RBCs from KAHRP-knockout parasites showed KAHRP contributes approximately 51% of the overall increase in membrane shear elastic modulus (rigidity) that occurs in P. falciparum-infected RBCs, a significantly greater contribution than PfEMP3 (~15%).\",\n      \"method\": \"Micropipette aspiration, gene knockout (kahrp deletion), quantitative biophysics\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — quantitative biophysical assay on clean knockout parasites, specific phenotypic readout with defined magnitude\",\n      \"pmids\": [\"11807013\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"Direct binding experiments showed KAHRP interacts with the cytoplasmic domain of PfEMP1 (VARC); three KAHRP fragments were identified that bind VARC, with two high-affinity binding regions mapping to the 63-residue histidine-rich region and the 70-residue 5' repeat region of KAHRP (Kd ~10^-7 M and ~3.3×10^-6 M respectively); deletion of both regions abolished VARC binding.\",\n      \"method\": \"In vitro binding assay (recombinant protein fragments), binding affinity measurements, deletion mutagenesis\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro binding reconstitution with quantitative Kd measurements and deletion mutagenesis confirming specific binding domains\",\n      \"pmids\": [\"10446142\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"The binding site for spectrin on KAHRP was mapped to a 72-amino-acid fragment (residues 370–441), and the reciprocal KAHRP-binding site on spectrin was localized to repeat 4 of alpha-spectrin (alpha N-5 fragment); resealing of the repeat 4 peptide into erythrocytes mislocalised KAHRP in parasitized cells, establishing that the KAHRP–spectrin interaction is critical for correct membrane localization of KAHRP.\",\n      \"method\": \"In vitro binding assay (recombinant fragments), competition assay, erythrocyte resealing experiment, immunofluorescence\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — in vitro domain mapping combined with functional erythrocyte resealing experiment showing in-cell consequence, multiple orthogonal methods\",\n      \"pmids\": [\"16006556\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Expression of mutant KAHRP constructs in transgenic P. falciparum showed that the C-terminal repeat region of KAHRP is critical for formation of functional knobs (assessed by atomic force and electron microscopy); the 5' repeat region of KAHRP is important for cross-linking to the host-cell cytoskeleton, required for knob protrusion and efficient adhesion under physiological flow conditions.\",\n      \"method\": \"Stable transgenic parasite lines expressing KAHRP domain mutants, atomic force microscopy, electron microscopy, flow adhesion assay\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — domain-specific mutants in live parasites with multiple structural and functional readouts\",\n      \"pmids\": [\"16507777\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"In vitro binding experiments demonstrated that the cytoplasmic domain of PfEMP1 (VAR_CD) binds to full-length KAHRP with an apparent Kd of ~10.7 nM; KAHRP polypeptides self-associate in solution to form knob-like structures and show binding to spectrin-actin-protein 4.1 complexes; VAR_CD also binds F-actin (Kd ~44.9 nM) and spectrin.\",\n      \"method\": \"In vitro binding assay, affinity measurements, self-association assay, co-sedimentation\",\n      \"journal\": \"Molecular and biochemical parasitology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — quantitative in vitro reconstitution showing KAHRP self-association and binding to host cytoskeletal components with Kd values, single lab\",\n      \"pmids\": [\"10838226\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"KAHRP, but not PfEMP1, PfEMP3, or RESA, binds to erythrocyte ankyrin R; the KAHRP binding site on ankyrin R was mapped to the D3 subdomain of the 89 kDa membrane-binding domain, and the ankyrin-binding segment on KAHRP was localized to a 79-residue sequence; loading erythrocytes with soluble D3 subdomain prevented KAHRP from migrating to the host cell membrane, leaving it diffusely distributed in the cytosol.\",\n      \"method\": \"In vitro binding assay, domain mapping, erythrocyte resealing/loading experiment, immunofluorescence\",\n      \"journal\": \"Biochimica et biophysica acta\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — in vitro domain mapping combined with functional erythrocyte loading experiment showing in-cell localization consequence, multiple orthogonal methods\",\n      \"pmids\": [\"24090929\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 1986,\n      \"finding\": \"Isolation of cDNA clones for KAHRP showed that in knobless mutants of P. falciparum the KAHRP gene has undergone a chromosomal rearrangement resulting in a deletion in the 3' coding sequence and a telomeric relocation of the truncated gene on chromosome 2, explaining loss of KAHRP mRNA and protein expression and knobless phenotype.\",\n      \"method\": \"cDNA cloning, Southern blotting, chromosomal mapping\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct molecular characterization linking gene deletion to protein loss and phenotype, single lab with clear genetic evidence\",\n      \"pmids\": [\"3016553\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 1987,\n      \"finding\": \"The complete gene sequence of KAHRP was determined; the gene contains a single intron at the 3' boundary of the signal peptide hydrophobic core; the protein contains a histidine-rich region and two separate repeat blocks (5' repeats related to SKKHKDNEDAESVK, and 3' repeats related to SKGATKEAST), both of which bear epitopes recognized by human antibodies during natural infection.\",\n      \"method\": \"cDNA and chromosomal clone sequencing, E. coli expression of repeat domains, human antibody reactivity assay\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — complete gene/protein sequence with functional validation of repeat domain immunogenicity, single foundational study\",\n      \"pmids\": [\"3301325\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 1987,\n      \"finding\": \"Immunoelectron microscopy using affinity-purified antibodies against recombinant KAHRP established that the protein is clustered on the cytoplasmic side of the erythrocyte membrane and is physically associated with the electron-dense knobs.\",\n      \"method\": \"Immunoelectron microscopy, indirect immunofluorescence, recombinant protein expression in E. coli\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct subcellular localization by immunoelectron microscopy with monospecific antibodies, single lab\",\n      \"pmids\": [\"3313387\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 1992,\n      \"finding\": \"Stage-specific nuclear run-on analysis demonstrated that KAHRP gene transcription is developmentally regulated during the intraerythrocytic cycle; a sequence motif with two-fold symmetry located 160 bp upstream of the RNA initiation site interacts with parasite nuclear extracts in a stage-specific manner correlating with transcriptional activity of the KAHRP gene.\",\n      \"method\": \"Nuclear run-on analysis, protein-DNA interaction assay (gel shift/footprinting), genomic sequence analysis\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct transcription assay plus protein-DNA interaction showing stage-specific regulation, single lab with two methods\",\n      \"pmids\": [\"1620601\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"The N-terminal protein export element (signal/PEXEL region) of KAHRP, when appended to the transmembrane and C-terminal domains of PfEMP1, was sufficient for efficient trafficking of those domains to the outside of the P. falciparum-infected RBC membrane; the physical state of exported proteins suggested trafficking as a complex rather than in vesicles.\",\n      \"method\": \"GFP chimera constructs, fluorescence microscopy, FRAP\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — chimeric construct trafficking experiment with FRAP, single lab, two methods\",\n      \"pmids\": [\"15692070\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"A mutated KAHRP construct with the PEXEL motif repositioned near the signal sequence was not cleaved by plasmepsin V and was not exported, despite retaining putative PI(3)P-binding residues; restoring the PEXEL to its original position restored processing by plasmepsin V and export, demonstrating that PEXEL position is conserved for co-translational processing and export.\",\n      \"method\": \"Site-directed mutagenesis of KAHRP PEXEL motif, transfection, export assay, biochemical processing analysis\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — mutant construct in live parasites with specific biochemical and export readout, single lab\",\n      \"pmids\": [\"26832821\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"In vitro binding assays showed that VARC phosphorylation by erythrocytic casein kinase II (CKII) alters the binding of VARC to KAHRP; inhibition of CKII reduced cytoadherence of infected RBCs to ICAM-1 and CSA, suggesting KAHRP–VARC interaction is modulated by CKII-mediated phosphorylation.\",\n      \"method\": \"In vitro binding assay, CKII inhibitor/enhancer treatment, phosphorylation assay, cytoadherence assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vitro and in vivo evidence for phosphorylation-dependent modulation of KAHRP–VARC interaction, single lab\",\n      \"pmids\": [\"19131328\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Electron tomography of detergent-insoluble skeletons from P. falciparum 3D7 schizonts revealed a highly organized knob skeleton comprising a spiral structure coated by an electron-dense layer; immuno-EM localized KAHRP within these structures, and connections from the knob skeleton to the erythrocyte cytoskeleton were observed.\",\n      \"method\": \"Electron tomography, immuno-electron microscopy, freeze-fracture scanning EM\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct structural localization of KAHRP by immuno-EM within tomographic context, single lab, multiple EM methods\",\n      \"pmids\": [\"26637786\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"3D7\"}]\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Biophysical and structural analyses showed that a repeat region in KAHRP preferentially associates with domains 10–14 of β-spectrin (proximal to the spectrin-ankyrin complex), while the PfEMP1 cytosolic domain interacts broadly with spectrin but shows preference for domain 17 of α-spectrin; structural models combined with prior data suggested a model for knob architecture.\",\n      \"method\": \"Biophysical binding assays, structural analysis, computational modeling\",\n      \"journal\": \"PLoS pathogens\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — biophysical domain mapping with structural and computational validation, single lab\",\n      \"pmids\": [\"28806784\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Correlative STORM-SEM showed KAHRP is delivered as individual modules that assemble in situ at the RBC membrane skeleton, giving a ring-shaped fluorescence profile around a dimpled disk visible by SEM; electron tomography revealed a spiral scaffold underlying assembled knobs; truncation of the KAHRP C-terminal region caused loss of ring structures, disruption of raised disks, and aberrant spiral scaffold formation; host cell actin remodeling (blocked by cytochalasin D) was required for knob assembly.\",\n      \"method\": \"Correlative STORM-SEM, electron tomography, KAHRP C-terminal truncation mutants, cytochalasin D treatment, super-resolution microscopy\",\n      \"journal\": \"PLoS pathogens\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal high-resolution imaging methods with domain truncation and pharmacological perturbation, defining assembly mechanism\",\n      \"pmids\": [\"31071194\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Super-resolution microscopy (single-molecule localization) showed KAHRP initially associates with ankyrin bridges in the erythrocyte skeleton but eventually colocalizes with remnant actin junctions; a 35 Å cryo-EM map of the spiral scaffold underlying knobs was obtained and a KAHRP-targeting nanoprobe was shown to bind close to the spiral; approximately 60 KAHRP molecules per knob were detected.\",\n      \"method\": \"Super-resolution single-molecule localization microscopy (SMLM), cryo-electron microscopy, KAHRP nanoprobe, quantitative fluorescence analysis\",\n      \"journal\": \"Molecular microbiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — cryo-EM structure combined with super-resolution localization and quantification, multiple orthogonal methods in single study\",\n      \"pmids\": [\"34514656\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Dynamic NMR and binding assays identified four positively charged linear sequence motifs of high intrinsic mobility in KAHRP that interact electrostatically with VARC (cytoplasmic domain of PfEMP1) in solution to form a 'fuzzy complex'; co-localization of KAHRP and VARC to membrane knobs was confirmed by immunofluorescence.\",\n      \"method\": \"NMR spectroscopy, in vitro binding assay, immunofluorescence co-localization\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — NMR-based structural characterization of interaction motifs combined with co-localization, single lab\",\n      \"pmids\": [\"25726759\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Co-immunoprecipitation assays demonstrated that KAHRP is in a complex with the parasite Hsp40 (KAHsp40/PF3D7_0201800), PfEMP3, and Hsp101; double IFA showed co-localization of KAHsp40 with KAHRP at the erythrocyte periphery in structures consistent with knobs.\",\n      \"method\": \"Co-immunoprecipitation, immunofluorescence assay (IFA), subcellular fractionation\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — co-IP identifying complex membership, supported by co-localization; single lab, does not establish KAHRP's own mechanistic role beyond complex membership\",\n      \"pmids\": [\"22970262\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Flow-based adhesion assay using KAHRP-knockout parasite lines showed that loss of KAHRP had a significant effect on the ability of parasitized RBCs to adhere under flow conditions, comparable in impact to loss of PfEMP3 but distinct from loss of RESA or MESA.\",\n      \"method\": \"Competitive flow-based adhesion assay, gene-knockout parasite lines\",\n      \"journal\": \"British journal of haematology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean knockout with quantitative flow adhesion assay, single lab\",\n      \"pmids\": [\"11918556\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"PfTBP (TATA-binding protein) was shown by supershift, footprinting, and chromatin immunoprecipitation assays to associate in vivo with a consensus TATA box sequence located 81 bp upstream of the KAHRP transcription start site, identifying a functional cis-acting element and its trans-acting factor for KAHRP promoter regulation.\",\n      \"method\": \"Supershift assay, DNase I footprinting, chromatin immunoprecipitation (ChIP)\",\n      \"journal\": \"Molecular and biochemical parasitology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods (footprinting, supershift, ChIP) establishing promoter mechanism, single lab\",\n      \"pmids\": [\"15760658\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 1994,\n      \"finding\": \"Mapping of endonuclease hypersensitive sites in P. falciparum chromatin revealed that spontaneous chromosome breakages within the KAHRP gene coding region occur preferentially within linker regions of nucleosomes with a periodicity of ~155 bp, corresponding to the P. falciparum nucleosome repeat unit, establishing that chromatin structure determines the sites of chromosome breakage.\",\n      \"method\": \"Mapping of endonuclease hypersensitive sites, nucleosome periodicity analysis, pulsed-field gel electrophoresis\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct chromatin structure mapping at KAHRP locus showing mechanistic basis for breakage, single lab\",\n      \"pmids\": [\"8065922\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"In P. berghei, a GFP construct bearing a KAHRP-like N-terminus (signal sequence + PEXEL/VTS motif) was exported into the erythrocyte cytosol, whereas a construct with a PfEMP1-like N-terminus (lacking signal sequence before PEXEL) was not, suggesting proteins with KAHRP-like architecture follow a distinct common export pathway.\",\n      \"method\": \"GFP reporter constructs, P. berghei transfection, fluorescence microscopy\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional export assay using KAHRP signal architecture in a heterologous Plasmodium system, single lab\",\n      \"pmids\": [\"20419102\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium berghei\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Confocal microscopy and FRAP showed that erythrocytes infected with a KAHRP-null parasite strain exhibit the same decrease in lateral mobility of host membrane proteins (band 3, glycophorin) as wild-type infected erythrocytes, indicating KAHRP does not contribute to immobilization of host membrane proteins.\",\n      \"method\": \"Confocal microscopy, FRAP, KAHRP-null parasite line\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — clean knockout with specific functional readout, but this is a negative result (KAHRP not involved in host protein immobilization)\",\n      \"pmids\": [\"14615371\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    }\n  ],\n  \"current_model\": \"KAHRP (PF3D7_0202000) is an exported P. falciparum protein that is essential for knob formation on infected erythrocytes: it is trafficked from the parasite endomembrane system via Maurer's clefts to the cytoplasmic face of the erythrocyte membrane, where it self-assembles into ring-shaped structures (~60 molecules/knob) that form a spiral scaffold anchored to the host spectrin-actin cytoskeleton through direct interactions with α-spectrin repeat 4 (via a 72-residue KAHRP fragment) and ankyrin R (via a 79-residue KAHRP segment); KAHRP's 5' repeat region cross-links to the cytoskeleton to drive knob protrusion, while its C-terminal repeat region is critical for functional knob formation; KAHRP also directly binds the cytoplasmic domain of PfEMP1 (VARC) through its histidine-rich and 5' repeat regions, an interaction modulated by erythrocytic casein kinase II phosphorylation of VARC; together, these interactions account for ~51% of the increased membrane rigidity of infected RBCs and are required for cytoadherence under physiological flow conditions.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"KAHRP (PF3D7_0202000) is an exported P. falciparum protein essential for assembling knobs on the surface of infected erythrocytes, structures required for cytoadherence of parasitized red cells under physiological shear stress [#0]. Following co-translational PEXEL processing by plasmepsin V, whose motif position is essential for export [#13], KAHRP is trafficked from the parasite endomembrane system through Maurer's clefts into the erythrocyte cytoplasm and finally into knobs, with distinct sequence elements governing individual steps of this pathway [#1]. At the cytoplasmic face of the host membrane KAHRP self-associates into knob-like structures [#6] and assembles in situ as individual modules into ring-shaped units (~60 molecules per knob) that build a spiral scaffold [#17, #18]. This scaffold is anchored to the host spectrin-actin cytoskeleton through direct, domain-mapped interactions: a 72-residue KAHRP fragment binds repeat 4 of α-spectrin [#4], a 79-residue segment binds the D3 subdomain of ankyrin R [#7], and disrupting either interaction mislocalizes KAHRP to the cytosol, establishing that cytoskeletal attachment governs correct membrane targeting [#4, #7]. KAHRP also directly binds the cytoplasmic domain of PfEMP1 (VARC) with high affinity through its histidine-rich and 5' repeat regions [#3, #6], forming an electrostatic 'fuzzy complex' [#19] whose strength is modulated by erythrocytic casein kinase II phosphorylation of VARC [#14]. Functionally, the 5' repeat region cross-links to the cytoskeleton to drive knob protrusion and adhesion, while the C-terminal repeat region is critical for functional knob formation and spiral scaffold integrity [#5, #17]; collectively these interactions account for roughly 51% of the increased membrane rigidity of infected red cells [#2]. KAHRP does not contribute to immobilization of host membrane proteins, indicating its mechanical role is confined to knob assembly [#25].\",\n  \"teleology\": [\n    {\n      \"year\": 1986,\n      \"claim\": \"Establishing the molecular basis of the knobless phenotype linked KAHRP gene integrity to knob formation, showing that loss of KAHRP expression underlies the knobless state.\",\n      \"evidence\": \"cDNA cloning, Southern blotting, and chromosomal mapping in knobless P. falciparum mutants\",\n      \"pmids\": [\"3016553\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Correlational: gene rearrangement linked to phenotype without direct functional rescue\", \"Did not define KAHRP molecular function\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 1987,\n      \"claim\": \"Sequencing and immunolocalization defined KAHRP's domain architecture and placed the protein physically at knobs, providing the structural foundation for later mechanistic dissection.\",\n      \"evidence\": \"Gene/protein sequencing plus immunoelectron microscopy with recombinant-protein antibodies\",\n      \"pmids\": [\"3301325\", \"3313387\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Function of the histidine-rich and repeat domains not yet tested\", \"No binding partners identified\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 1997,\n      \"claim\": \"Targeted disruption resolved whether KAHRP is merely a knob component or is required for the adhesion phenotype, demonstrating it is essential for knob formation and flow-based cytoadherence.\",\n      \"evidence\": \"Gene knockout with static and flow-based CD36 adhesion assays\",\n      \"pmids\": [\"9108483\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not identify the molecular interactions underlying knob assembly\", \"Contribution to membrane mechanics not quantified\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2000,\n      \"claim\": \"In vitro reconstitution addressed how KAHRP bridges the parasite adhesin to the host skeleton, showing high-affinity binding to the PfEMP1 cytoplasmic domain, self-association into knob-like structures, and binding to spectrin-actin-4.1 complexes.\",\n      \"evidence\": \"In vitro binding, affinity measurements, self-association and co-sedimentation assays\",\n      \"pmids\": [\"10838226\", \"10446142\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In-cell relevance of the mapped binding regions not yet tested\", \"Reciprocal binding sites on host proteins not defined\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"Live-cell trafficking analysis defined the export route of KAHRP, placing Maurer's clefts as an intermediate depot and mapping sequence elements to individual trafficking steps.\",\n      \"evidence\": \"GFP fusions, live microscopy, FRAP, and domain deletion analysis\",\n      \"pmids\": [\"11598007\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular machinery mediating each step not identified\", \"PEXEL processing requirement not yet resolved\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Quantitative biophysics answered how much KAHRP contributes to the mechanical stiffening of infected cells, showing it accounts for ~51% of the increased membrane shear modulus.\",\n      \"evidence\": \"Micropipette aspiration of KAHRP-knockout versus wild-type infected RBCs; competitive flow adhesion assays\",\n      \"pmids\": [\"11807013\", \"11918556\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Which molecular interactions produce the rigidity increase not resolved by this assay\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Domain mapping and in-cell perturbation defined KAHRP's spectrin anchor and its export signal, showing the α-spectrin repeat 4 interaction is required for correct membrane localization and that the N-terminal export element can traffic heterologous cargo.\",\n      \"evidence\": \"Recombinant fragment binding, erythrocyte resealing of competing peptide, immunofluorescence, and GFP chimera trafficking\",\n      \"pmids\": [\"16006556\", \"15692070\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Additional cytoskeletal anchors not yet identified\", \"Whether spectrin binding drives knob mechanics untested\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Domain-specific transgenic mutants assigned functions to KAHRP's repeat regions, showing the 5' repeats mediate cytoskeletal cross-linking and protrusion while the C-terminal repeats are required for functional knob formation.\",\n      \"evidence\": \"Transgenic parasites expressing KAHRP domain mutants analyzed by atomic force microscopy, electron microscopy, and flow adhesion\",\n      \"pmids\": [\"16507777\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of C-terminal repeat function not defined\", \"Molecular partner of the C-terminal region unknown\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Identifying casein kinase II modulation showed the KAHRP-PfEMP1 interaction is regulated by host-cell phosphorylation, linking a signaling input to cytoadherence.\",\n      \"evidence\": \"In vitro binding with CKII treatment, phosphorylation assay, and cytoadherence to ICAM-1/CSA\",\n      \"pmids\": [\"19131328\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Physiological trigger controlling CKII activity not defined\", \"Effect on knob architecture not measured\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Discovery of the ankyrin R interaction defined a second, KAHRP-specific host anchor required for membrane targeting, distinguishing KAHRP from other exported proteins.\",\n      \"evidence\": \"In vitro binding, domain mapping to ankyrin D3 subdomain, and erythrocyte D3-loading with immunofluorescence\",\n      \"pmids\": [\"24090929\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Relative contributions of spectrin versus ankyrin binding to assembly not resolved\", \"Order of anchor engagement during assembly untested at this stage\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Structural and complex analyses refined the KAHRP-PfEMP1 interaction and placed KAHRP in a knob-associated protein complex, describing an electrostatic fuzzy complex and membership with Hsp40, PfEMP3 and Hsp101.\",\n      \"evidence\": \"NMR of KAHRP-VARC binding motifs, immunofluorescence co-localization, electron tomography, and co-immunoprecipitation\",\n      \"pmids\": [\"25726759\", \"26637786\", \"22970262\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Co-IP establishes complex membership but not KAHRP's specific role within it\", \"Stoichiometry and dynamics of the fuzzy complex in vivo unknown\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Preferential spectrin sub-domain mapping refined the architectural model, showing KAHRP repeats associate with β-spectrin domains near the spectrin-ankyrin junction distinct from PfEMP1's preferred α-spectrin site.\",\n      \"evidence\": \"Biophysical binding assays with structural analysis and computational modeling\",\n      \"pmids\": [\"28806784\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Model not validated by high-resolution structure of the assembled interface\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"High-resolution correlative imaging resolved how KAHRP assembles into knobs, showing in-situ modular assembly into rings over a spiral scaffold that depends on the C-terminal region and host actin remodeling.\",\n      \"evidence\": \"Correlative STORM-SEM, electron tomography, C-terminal truncation mutants, and cytochalasin D treatment\",\n      \"pmids\": [\"31071194\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular trigger initiating spiral nucleation not defined\", \"Role of actin junction remodeling relative to spectrin/ankyrin anchoring unresolved\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Cryo-EM and single-molecule localization quantified knob composition and captured a shift in KAHRP's host anchoring during assembly, from ankyrin bridges to remnant actin junctions, with ~60 KAHRP molecules per knob.\",\n      \"evidence\": \"Single-molecule localization microscopy, 35 Å cryo-EM of the spiral scaffold, and a KAHRP-targeting nanoprobe\",\n      \"pmids\": [\"34514656\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Atomic-resolution structure of KAHRP within the scaffold not yet achieved\", \"Mechanism driving the ankyrin-to-actin transition unknown\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"A high-resolution molecular structure of KAHRP within the assembled spiral scaffold, and the mechanism controlling ordered engagement of its multiple host anchors during knob nucleation, remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No atomic-resolution structure of KAHRP in situ\", \"Order and regulation of spectrin, ankyrin, and actin engagement during assembly not fully defined\", \"How PfEMP1 loading is coordinated with scaffold maturation unknown\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0005200\", \"supporting_discovery_ids\": [0, 5, 17, 18]},\n      {\"term_id\": \"GO:0042803\", \"supporting_discovery_ids\": [6, 17]},\n      {\"term_id\": \"GO:0008092\", \"supporting_discovery_ids\": [4, 6, 7, 16]},\n      {\"term_id\": \"GO:0005515\", \"supporting_discovery_ids\": [3, 6, 7, 14, 19, 20]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0020030\", \"supporting_discovery_ids\": [10, 15, 17, 18]},\n      {\"term_id\": \"GO:0032432\", \"supporting_discovery_ids\": [17, 18]},\n      {\"term_id\": \"GO:0020036\", \"supporting_discovery_ids\": [1]},\n      {\"term_id\": \"GO:0020020\", \"supporting_discovery_ids\": [10, 4, 7]},\n      {\"term_id\": \"GO:0020002\", \"supporting_discovery_ids\": [1, 12, 24]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0046718\", \"supporting_discovery_ids\": [1, 12, 13, 24]},\n      {\"term_id\": \"GO:0052192\", \"supporting_discovery_ids\": [0, 5, 21]},\n      {\"term_id\": \"GO:0007155\", \"supporting_discovery_ids\": [0, 3, 14, 21]}\n    ],\n    \"complexes\": [\n      \"Knob spiral scaffold (~60 KAHRP molecules per knob)\",\n      \"KAHRP–PfEMP1(VARC) fuzzy complex\",\n      \"KAHRP–α-spectrin repeat 4 complex\",\n      \"KAHRP–ankyrin R (D3 subdomain) complex\",\n      \"KAHRP / KAHsp40 (PF3D7_0201800) / PfEMP3 / Hsp101 complex\"\n    ],\n    \"partners\": [\n      \"PfEMP1 cytoplasmic domain (VARC/VAR_CD)\",\n      \"erythrocyte α-spectrin (repeat 4)\",\n      \"erythrocyte β-spectrin (domains 10–14)\",\n      \"erythrocyte ankyrin R (D3 subdomain)\",\n      \"spectrin-actin-protein 4.1 complex / F-actin\",\n      \"KAHsp40 (PF3D7_0201800)\",\n      \"PfEMP3\",\n      \"Hsp101\",\n      \"plasmepsin V (PEXEL processing)\",\n      \"erythrocytic casein kinase II (via VARC phosphorylation)\"\n    ],\n    \"other_free_text\": [\n      \"KAHRP contains a signal peptide with a single intron at the 3' boundary of its hydrophobic core, a histidine-rich region, a 5' repeat block (SKKHKDNEDAESVK-related) and a 3' repeat block (SKGATKEAST-related); both repeat blocks carry epitopes recognized by human infection antibodies [#9].\",\n      \"Export requires a correctly positioned PEXEL motif for plasmepsin V co-translational processing [#13].\",\n      \"KAHRP transcription is stage-specific during the intraerythrocytic cycle, regulated via an upstream two-fold-symmetric motif and a TATA box bound by PfTBP [#11, #22].\",\n      \"In knobless mutants a chromosomal rearrangement deletes the 3' coding sequence and relocates a truncated KAHRP gene, abolishing expression [#8]; chromosome breakage within the coding region occurs preferentially at nucleosome linker regions [#23].\",\n      \"KAHRP does not contribute to immobilization of host membrane proteins band 3 and glycophorin [#25].\",\n      \"In P. berghei, a KAHRP-like N-terminal architecture (signal sequence plus PEXEL/VTS) is sufficient for export into the erythrocyte cytosol, unlike a PfEMP1-like N-terminus [#24].\"\n    ]\n  }\n}","audit_flag":null,"strains":[{"strain":"Pf3D7","gene_id":"PF3D7_0202000","name":null,"product":"knob-associated histidine-rich protein","uniprot_acc":null,"chromosome":null,"start_pos":null},{"strain":"PkH","gene_id":"PKNH_1325700","name":null,"product":"knob-associated histidine-rich protein, putative","uniprot_acc":null,"chromosome":null,"start_pos":null}],"gene_symbol":"KAHRP","evaluation":null}