{"gene":"PF3D7_0905400","run_date":"2026-09-08T12:51:27","timeline":{"discoveries":[{"year":1991,"finding":"RhopH3 (PF3D7_0905400) was identified as a 105 kDa protein located in the rhoptries of P. falciparum merozoites, encoded by a genomic sequence with 7 exons including 2 mini-exons, lacking tandem repeats, and containing B cell epitopes that induce antibody responses during natural infection.","method":"cDNA/genomic cloning, Western blotting, immunoelectron microscopy","journal":"Molecular and biochemical parasitology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Western blotting and immunoelectron microscopy establishing rhoptry localization, single lab with two orthogonal methods","pmids":["1775161"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":1993,"finding":"During rhoptry biogenesis in P. falciparum, RhopH3 (as Rhop-H3) is first detectable in small granular low-density vesicle compartments (~1.12 g/ml sucrose) at the four-nucleus stage together with RhopH2, then later appears in higher-density mature rhoptries (~1.16 g/ml) at the 16-nucleus stage; RhopH3 mRNA peaks at the 8-nucleus stage, demonstrating stage-specific expression coordinated with rhoptry biogenesis.","method":"Subcellular fractionation, sucrose gradient centrifugation, immunoelectron microscopy, Northern blotting","journal":"Molecular and biochemical parasitology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods (fractionation, IEM, Northern blot) in single lab establishing trafficking sequence","pmids":["8433718"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":1994,"finding":"Monoclonal antibodies recognizing the RhopH complex immunoprecipitated RhopH3 together with RhopH1 and RhopH2, confirming RhopH3 is a non-covalently associated component of the high molecular weight rhoptry complex; some mAbs recognized RhopH3 alone while others co-precipitated RhopH3 with RhopH1 or RhopH2, indicating distinct epitope accessibility.","method":"Immunoprecipitation, immunofluorescence, immunoelectron microscopy","journal":"Parasitology","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — immunoprecipitation across 21 monoclonal antibodies providing convergent evidence for complex membership, single lab","pmids":["7517517"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":1997,"finding":"Two major monoclonal antibody binding sites on RhopH3 were mapped to amino acids 823–828 (TDNTY/TDNTYK) and ~residue 850 of the C-terminal region. Antibodies to the ~850 site reacted exclusively with the 110 kDa form of RhopH3 but not the 105 kDa form, providing evidence that the 105 kDa RhopH3 polypeptide is generated from the 110 kDa form by C-terminal proteolytic processing.","method":"Overlapping peptide scanning, systematic amino acid replacement, Western blotting with isoform-specific antisera","journal":"Molecular and biochemical parasitology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — systematic peptide mapping combined with isoform-specific antisera, single lab but multiple orthogonal approaches","pmids":["9106189"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2003,"finding":"RhopH3 and RAP1 were found in close apposition with RAMA in early vesicles/pre-rhoptries, suggesting direct protein-protein interactions; this co-localization was disrupted by brefeldin A, implicating RAMA in trafficking RhopH3 into rhoptries via the Golgi-vesicle pathway.","method":"Immunofluorescence microscopy, brefeldin A inhibition, immunoelectron microscopy","journal":"The Journal of biological chemistry","confidence":"Low","confidence_rationale":"Tier 3 / Weak — co-localization-based inference of interaction, no direct pull-down for RhopH3 specifically, single lab","pmids":["14613941"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2008,"finding":"After red blood cell invasion by P. falciparum, the merozoite-acquired RhopH complex (including RhopH3) is transferred not only to the parasitophorous vacuole membrane but also to defined domains of the red blood cell cytoplasm, with possible transient association with Maurer's clefts.","method":"Immunofluorescence microscopy, subcellular fractionation of infected erythrocytes","journal":"Molecular and biochemical parasitology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — immunofluorescence and fractionation providing concordant subcellular localization data, single lab","pmids":["18508137"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2008,"finding":"Fourteen synthetic peptides derived from RhopH3 (PF3D7_0905400) bound to human erythrocytes with saturable kinetics and nanomolar dissociation constants; binding was partially sensitive to sialic acid removal and glycoprotein-disrupting enzyme treatments. These peptides inhibited P. falciparum merozoite invasion of erythrocytes by up to 90% at 200 µM.","method":"Synthetic peptide erythrocyte binding assays, enzyme-treated erythrocytes, cross-linking assays, circular dichroism, invasion inhibition assays","journal":"Protein science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal binding and functional assays in single lab establishing erythrocyte-binding regions","pmids":["18593818"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2010,"finding":"Proteomic pull-down experiments with anti-PfMSP-1 and anti-PfRhopH3 antibodies from merozoite lysates identified a complex containing PfRhopH3, PfMSP-1(42), PfRhopH1, PfRAP-1, PfRAP-2, MSP-3, MSP-6, MSP-7, and MSP-9, present at schizont/merozoite stages but not ring stage. Anti-PfRhopH3 antibodies blocked erythrocyte invasion.","method":"Co-immunoprecipitation / pull-down, tandem mass spectrometry, invasion inhibition assay","journal":"Journal of proteome research","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — reciprocal pulldown with MS identification and functional invasion inhibition, single lab","pmids":["21175202"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2015,"finding":"The RNA-binding protein PfAlba1 binds RhopH3 mRNA in trophozoites and represses its translation at this stage; release of the mRNA from PfAlba1 complex in mature schizonts correlates with protein synthesis, establishing post-transcriptional translational timing control of RhopH3 expression.","method":"RNA immunoprecipitation with deep sequencing, ribosome occupancy, mRNA steady-state level analysis, epitope-tagged overexpression","journal":"Genome biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — RIP-seq plus translational profiling providing mechanistic evidence, single lab with multiple orthogonal methods","pmids":["26415947"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2014,"finding":"A direct biochemical interaction between RhopH3 and human erythrocyte band 3 (specifically the 5ABC extracellular region) was established by yeast two-hybrid screen and confirmed biochemically. RhopH3 forms a ternary complex with MSP1(19) and band 3 5ABC, and a recombinant segment of RhopH3 inhibited P. falciparum invasion of erythrocytes, implicating this interaction in the sialic acid-independent invasion pathway.","method":"Yeast two-hybrid, co-immunoprecipitation, recombinant protein invasion inhibition assay, anti-peptide antibody inhibition assay","journal":"Biochimica et biophysica acta","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — yeast two-hybrid plus biochemical co-IP plus functional inhibition, single lab with multiple orthogonal methods","pmids":["25157665"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":"3D7"}]},{"year":2017,"finding":"Conditional knockdown of RhopH3 in P. falciparum substantially reduces erythrocyte invasion capacity. Parasites that do invade despite RhopH3 knockdown show defective nutrient import (new permeability pathway / PSAC activity) and die. Knockdown of RhopH3 also disrupts the entire RhopH complex, interfering with organellar targeting and subsequent trafficking of all complex members.","method":"Conditional knockdown (DiCre-based truncation), invasion assays, sorbitol/nutrient uptake assays, immunofluorescence, Western blotting","journal":"eLife","confidence":"High","confidence_rationale":"Tier 2 / Strong — conditional genetic knockdown with specific invasion, nutrient uptake, and complex assembly phenotypes, replicated across two independent labs (PMIDs 28252384 and 28221136)","pmids":["28252384"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":"3D7"}]},{"year":2017,"finding":"Conditional knockdown of RhopH3 in P. falciparum disrupts the entire RhopH complex assembly, interfering with organellar (rhoptry) targeting; knockdown abolishes nutrient channel (PSAC) activity; rhoph3 gene knockout was not viable, confirming RhopH3 is essential. RhopH3 contributes to erythrocyte invasion either through ligand-receptor interactions or subsequent parasite internalization steps.","method":"Conditional knockdown, gene knockout attempt, nutrient uptake assays, protein trafficking assays","journal":"eLife","confidence":"High","confidence_rationale":"Tier 2 / Strong — conditional knockdown plus failed knockout plus functional channel assays, independently replicating findings from PMID 28252384","pmids":["28221136"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2017,"finding":"RhopH3 interacts with RhopH2, RhopH1, the erythrocyte cytoskeleton, and exported proteins involved in host cell remodeling, as shown by co-immunoprecipitation in the context of investigating the RhopH complex. Knockdown of RhopH2 (which depletes the RhopH2–RhopH3 interaction) leads to reduced nutrient and cofactor uptake and decreased pyrimidine synthesis.","method":"Co-immunoprecipitation, conditional knockdown of RhopH2, metabolomics, growth assays","journal":"eLife","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — co-IP establishing interaction partners of RhopH3, with functional metabolic readout from RhopH2 knockdown affecting the complex, single lab","pmids":["28252383"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":"3D7"}]},{"year":2017,"finding":"Human Cyclophilin B (present on erythrocyte surface) acts as a receptor for RhopH3 (PF3D7_0905400) during merozoite invasion. RhopH3 binds to red blood cells, and Cyclosporin A treatment (blocking Cyclophilin B) prevents merozoite invasion. A multi-protein complex involving Cyclophilin B, Basigin, RhopH3, and PfRh5 was identified.","method":"Localization and binding studies, co-immunoprecipitation, invasion inhibition with Cyclosporin A and peptide CDP3","journal":"Nature communications","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — co-IP and functional inhibition data, single lab, multiple orthogonal approaches but no reconstitution","pmids":["29146974"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2020,"finding":"RhopH3 is phosphorylated at serine 804 (S804) in P. falciparum parasites. CRISPR-Cas9 mutation of S804 to alanine (phosphomutant R3_S804A) demonstrated that this phosphorylation is critical for RBC invasion but not intraerythrocytic development. S804 phosphorylation regulates RhopH3 localization to rhoptries and its discharge from the parasite. PfCDPK1 was identified as a candidate kinase responsible for RhopH3-S804 phosphorylation, and it regulates RhopH3 secretion.","method":"CRISPR-Cas9 phosphomutant generation, invasion assays, immunofluorescence localization, kinase candidate identification","journal":"mBio","confidence":"High","confidence_rationale":"Tier 2 / Moderate — CRISPR-based active-site mutagenesis establishing phosphorylation-dependent localization and function, single lab with multiple orthogonal readouts","pmids":["33024030"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":"3D7"}]},{"year":2020,"finding":"rhoph3 cannot be disrupted (knockout not viable) in P. falciparum because nutrient uptake is abolished in its absence, in contrast to clag3 which can be knocked out without abolishing transport under standard conditions. This establishes RhopH3 as uniquely essential for PSAC/NPP activity.","method":"Gene knockout attempts, sorbitol/nutrient uptake assays, genetic cross linkage analysis","journal":"PLoS pathogens","confidence":"High","confidence_rationale":"Tier 2 / Strong — failed knockout combined with functional channel assays, replicating essentiality finding from multiple independent labs","pmids":["32069335"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2021,"finding":"Cryo-EM structure of the native soluble RhopH trafficking complex at 2.9 Å resolution reveals RhopH3 forms large binding interfaces with CLAG3.1 but makes minimal direct contact with RhopH2. The complex assembles with 1:1:1 stoichiometry (CLAG3:RhopH2:RhopH3). RhopH3 contributes to stabilization via extensive disulfide bonding (contributing to 13 intramolecular disulfide bonds across the complex). Predicted transmembrane helices of CLAG3 are shielded within the soluble complex core.","method":"Single-particle cryo-EM (2.9 Å), mass spectrometry, cryoID structural determination of endogenous complex","journal":"eLife","confidence":"High","confidence_rationale":"Tier 1 / Strong — atomic-resolution cryo-EM structure of the endogenous complex, confirmed by MS stoichiometry, two independent structural studies (PMIDs 33393463 and 34446549)","pmids":["33393463"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2021,"finding":"Cryo-EM structure of the native RhopH complex shows CLAG3.1 is positioned centrally between RhopH2 and RhopH3, with RhopH3 sharing a substantial binding interface with CLAG3.1. RhopH3 stabilization involves intramolecular disulfide bonds; 13 disulfide bonds total stabilize the complex. The putative CLAG3 transmembrane helix (residues 1210–1223) is buried in a helical bundle, suggesting that membrane insertion requires a large conformational rearrangement, possibly triggered by allosteric disulfide bond breakage.","method":"Cryo-EM structure determination, mass spectrometry, cryoID program for subunit identification","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1 / Strong — independent atomic-resolution cryo-EM structure of native complex confirming RhopH3 binding interfaces, replicating PMID 33393463","pmids":["34446549"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2021,"finding":"Five exported proteins (including the most strongly associated PF3D7_1401200) interact with all members of the RhopH complex (CLAG3, RhopH2, RhopH3) as shown by reciprocal immunoprecipitation, but conditional knockdown of these proteins had no effect on NPP/sorbitol uptake activity. Additional protein complexes (cytoskeletal and Maurer's cleft/J-dot complexes) associated with RhopH3-containing complex were identified by MS proteomics.","method":"Reciprocal co-immunoprecipitation, conditional knockdown, sorbitol/NPP uptake assay, mass spectrometry proteomics","journal":"Cellular microbiology","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — reciprocal co-IP and mass spectrometry identifying RhopH3 interaction partners in exported context, single lab","pmids":["33774908"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":"3D7"}]},{"year":2022,"finding":"During merozoite invasion, RhopH3 and RhopH2 are released into the nascent parasitophorous vacuole (not directly into the host cell cytoplasm as CLAG3 is), and the full RhopH complex has not yet formed at this point. Export of RhopH2 and RhopH3 from the parasitophorous vacuole into the erythrocyte cytoplasm enables assembly of CLAG3/RhopH2/RhopH3 complexes and their incorporation into the host cell membrane, coinciding with activation of nutrient uptake. This compartmentalization prevents premature channel assembly.","method":"Live-cell imaging, immunofluorescence, conditional knockdown, nutrient uptake assays, super-resolution microscopy","journal":"Communications biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal imaging and functional methods establishing distinct trafficking routes and sequential assembly, single lab but rigorous","pmids":["35393572"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":"3D7"}]},{"year":2026,"finding":"In P. vivax, the RhopH3 homologue (PvRhopH3) binds human erythrocytes; three expressed recombinant regions (R1, R2, R3) were tested and regions R1 and R3 showed erythrocyte binding capability by immunoprecipitation and rosette-formation assays, with R1 having the highest binding rates.","method":"Recombinant protein expression, immunoprecipitation, rosette-formation erythrocyte binding assay","journal":"Acta tropica","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — two orthogonal binding assays (co-IP and rosette assay) identifying erythrocyte-binding regions, single lab","pmids":["42314857"],"is_preprint":false,"attribution":[{"species":"Plasmodium vivax","strain":""}]}],"current_model":"RhopH3 (PF3D7_0905400) is an essential ~105–110 kDa rhoptry protein that assembles as a 1:1:1 soluble complex with CLAG3 and RhopH2 (the RhopH complex), whose cryo-EM structure shows RhopH3 forms large interfaces exclusively with CLAG3; during invasion RhopH3 is discharged into the parasitophorous vacuole (separately from CLAG3), then exported through the PTEX translocon into the erythrocyte cytoplasm where it assembles with CLAG3 and RhopH2 and inserts into the erythrocyte membrane to form the plasmodial surface anion channel (PSAC/NPP) essential for nutrient uptake; RhopH3 also contributes directly to erythrocyte invasion through interactions with host receptors including band 3 and Cyclophilin B; its localization to rhoptries and discharge competence are regulated by phosphorylation at serine 804, likely by PfCDPK1; and its mRNA translation timing is controlled by the RNA-binding protein PfAlba1."},"narrative":{"mechanistic_narrative":"RhopH3 (PF3D7_0905400) is an essential rhoptry protein of P. falciparum that is indispensable both for erythrocyte invasion and for establishing the nutrient-uptake channel of the infected red cell [PMID:1775161, PMID:28252384, PMID:28221136]. It assembles non-covalently with CLAG3 and RhopH2 into the high molecular weight RhopH complex [PMID:7517517, PMID:33393463], and cryo-EM of the native soluble complex resolves its architecture at atomic resolution: RhopH3 forms a large binding interface with CLAG3 while making minimal direct contact with RhopH2, and contributes to the extensive intramolecular disulfide bonding that shields CLAG3's putative transmembrane helix within the complex core [PMID:33393463, PMID:34446549]. RhopH3 is required for correct rhoptry targeting and trafficking of the entire complex, and its conditional knockdown both reduces invasion and abolishes new-permeability-pathway/PSAC activity in parasites that do invade; unlike clag3, rhoph3 cannot be deleted, marking it as uniquely essential for channel function [PMID:28252384, PMID:28221136, PMID:32069335]. During invasion RhopH3 and RhopH2 are discharged into the nascent parasitophorous vacuole rather than directly into the host cytoplasm, and only after export into the erythrocyte does the CLAG3/RhopH2/RhopH3 channel assemble and activate nutrient uptake, a compartmentalization that prevents premature channel formation [PMID:35393572]. RhopH3 also engages host determinants directly, binding erythrocyte band 3 (5ABC region) as part of a ternary complex with MSP1(19) in the sialic-acid-independent invasion pathway [PMID:25157665] and using surface Cyclophilin B as a receptor [PMID:29146974]. Its function is gated by phosphorylation at serine 804, which controls rhoptry localization and discharge and is critical for invasion, with PfCDPK1 identified as the candidate kinase [PMID:33024030], while its translation timing is repressed post-transcriptionally by the RNA-binding protein PfAlba1 until schizogony [PMID:26415947].","teleology":[{"year":1991,"claim":"Establishing that RhopH3 is a defined rhoptry protein created the molecular entity on which all subsequent invasion and channel work would build.","evidence":"cDNA/genomic cloning with Western blotting and immunoelectron microscopy in P. falciparum merozoites","pmids":["1775161"],"confidence":"Medium","gaps":["No function assigned at identification","Relationship to other rhoptry proteins not yet defined"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":1993,"claim":"Tracking RhopH3 through rhoptry biogenesis showed its expression and trafficking are stage-coordinated with organelle maturation, framing it as a regulated rhoptry cargo.","evidence":"Subcellular fractionation, sucrose gradients, immunoelectron microscopy and Northern blotting across nuclear division stages","pmids":["8433718"],"confidence":"Medium","gaps":["Trafficking signals not identified","Mechanism coordinating mRNA and protein timing unknown at this stage"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":1994,"claim":"Immunoprecipitation resolved whether RhopH3 acts alone or in a complex, defining it as a non-covalent member of the high molecular weight rhoptry complex.","evidence":"Immunoprecipitation with a panel of monoclonal antibodies plus immunofluorescence/immuno-EM","pmids":["7517517"],"confidence":"Medium","gaps":["Stoichiometry and binding interfaces undefined","Functional consequence of complex membership unknown"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":1997,"claim":"Epitope mapping distinguished a 110 kDa precursor from a 105 kDa product, establishing that RhopH3 undergoes C-terminal proteolytic processing.","evidence":"Overlapping peptide scanning and isoform-specific antisera by Western blotting","pmids":["9106189"],"confidence":"Medium","gaps":["Protease responsible not identified","Functional role of processing not determined"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2003,"claim":"Co-localization with RAMA implicated the Golgi-vesicle pathway in delivering RhopH3 to rhoptries, addressing how the protein reaches its organelle.","evidence":"Immunofluorescence, brefeldin A inhibition and immuno-EM in P. falciparum","pmids":["14613941"],"confidence":"Low","gaps":["Co-localization inference without direct RhopH3 pull-down","Direct RAMA-RhopH3 interaction not demonstrated","Single lab"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2008,"claim":"Peptide-binding and invasion-inhibition experiments provided the first evidence that RhopH3 engages the erythrocyte surface during invasion.","evidence":"Synthetic peptide erythrocyte-binding assays with enzyme-treated cells and invasion inhibition in P. falciparum","pmids":["18593818"],"confidence":"Medium","gaps":["Erythrocyte receptor not identified at this stage","Peptide binding may not reflect native protein geometry"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2008,"claim":"Following the RhopH complex after invasion revealed transfer beyond the parasite into the erythrocyte cytoplasm, foreshadowing a host-cell role for RhopH3.","evidence":"Immunofluorescence and subcellular fractionation of infected erythrocytes","pmids":["18508137"],"confidence":"Medium","gaps":["Export mechanism undefined","Functional consequence in host cytoplasm not yet linked to nutrient transport"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2010,"claim":"Reciprocal pull-downs placed RhopH3 in a broader merozoite invasion assembly and showed anti-RhopH3 antibodies block invasion, functionally implicating it in RBC entry.","evidence":"Co-immunoprecipitation with tandem MS and invasion inhibition from merozoite lysates","pmids":["21175202"],"confidence":"Medium","gaps":["Direct versus indirect associations not resolved","Which interactions are functionally required unclear"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2014,"claim":"Identifying band 3 as a direct RhopH3 ligand gave a molecular receptor for its sialic-acid-independent invasion role.","evidence":"Yeast two-hybrid, co-IP, ternary complex reconstitution and recombinant-protein invasion inhibition","pmids":["25157665"],"confidence":"Medium","gaps":["Binding region on RhopH3 not mapped to atomic detail","Relative contribution versus other receptors unquantified"],"attribution":[{"species":"Plasmodium falciparum","strain":"3D7"}]},{"year":2015,"claim":"RIP-seq and translational profiling explained how RhopH3 protein appears only at the right stage, identifying PfAlba1-mediated translational repression.","evidence":"RNA immunoprecipitation-seq, ribosome occupancy and mRNA level analysis with tagged overexpression","pmids":["26415947"],"confidence":"Medium","gaps":["Signal releasing the mRNA in schizonts unknown","Direct PfAlba1 binding site on RhopH3 mRNA not mapped"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2017,"claim":"Conditional knockdown and failed knockout established RhopH3 as essential, required for complex assembly/trafficking, invasion, and PSAC-mediated nutrient uptake.","evidence":"DiCre conditional knockdown, knockout attempts, invasion assays, sorbitol/nutrient uptake and trafficking readouts across two independent labs","pmids":["28252384","28221136"],"confidence":"High","gaps":["Separating invasion role from channel role at the molecular level incomplete","Whether RhopH3 forms channel pore directly unknown"],"attribution":[{"species":"Plasmodium falciparum","strain":"3D7"}]},{"year":2017,"claim":"Co-IP tied RhopH3 to RhopH2, RhopH1, host cytoskeleton and exported remodeling proteins, and metabolic assays linked complex integrity to nutrient/cofactor uptake and pyrimidine synthesis.","evidence":"Co-immunoprecipitation with conditional RhopH2 knockdown, metabolomics and growth assays","pmids":["28252383"],"confidence":"Medium","gaps":["Metabolic phenotype driven via RhopH2 knockdown rather than RhopH3 directly","Direct cytoskeleton contacts of RhopH3 not resolved"],"attribution":[{"species":"Plasmodium falciparum","strain":"3D7"}]},{"year":2017,"claim":"Identifying erythrocyte-surface Cyclophilin B as a RhopH3 receptor added a second host determinant and placed RhopH3 in a receptor complex with Basigin and PfRh5.","evidence":"Localization/binding studies, co-IP and invasion inhibition with Cyclosporin A and peptide CDP3","pmids":["29146974"],"confidence":"Medium","gaps":["Direct versus complex-mediated RhopH3-Cyclophilin B binding not fully separated","No reconstitution of the receptor complex"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2020,"claim":"Phosphomutant analysis showed S804 phosphorylation gates RhopH3 rhoptry localization and discharge and is critical for invasion, naming PfCDPK1 as candidate kinase.","evidence":"CRISPR-Cas9 S804A mutant, invasion assays, immunofluorescence localization and kinase candidate identification in P. falciparum 3D7","pmids":["33024030"],"confidence":"High","gaps":["Direct PfCDPK1 phosphorylation of RhopH3 not biochemically proven","How phosphorylation mechanistically controls discharge unresolved"],"attribution":[{"species":"Plasmodium falciparum","strain":"3D7"}]},{"year":2020,"claim":"Comparing rhoph3 with clag3 showed only RhopH3 is strictly required for nutrient uptake, defining its unique essentiality for PSAC/NPP activity.","evidence":"Knockout attempts, sorbitol/nutrient uptake assays and genetic cross linkage analysis","pmids":["32069335"],"confidence":"High","gaps":["Molecular basis of RhopH3's non-redundant role in the channel undefined","Whether RhopH3 contributes to conductive pathway itself unknown"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2021,"claim":"Cryo-EM structures of the native soluble complex resolved RhopH3's architecture, showing it interfaces largely with CLAG3, minimally with RhopH2, and helps shield CLAG3's transmembrane helix via disulfide bonding.","evidence":"Single-particle cryo-EM at 2.9 A with MS stoichiometry and cryoID, two independent structural studies","pmids":["33393463","34446549"],"confidence":"High","gaps":["Membrane-inserted channel conformation not captured","Trigger for the conformational change to membrane insertion unresolved"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2021,"claim":"Reciprocal IP defined exported and cytoskeletal/Maurer's cleft partners of the RhopH3 complex, but their knockdown left NPP activity intact, distinguishing associated proteins from channel-essential ones.","evidence":"Reciprocal co-IP, conditional knockdown, sorbitol/NPP uptake assay and MS proteomics in P. falciparum 3D7","pmids":["33774908"],"confidence":"Medium","gaps":["Functional role of the exported partners undefined","Direct binding to RhopH3 versus other complex members not resolved"],"attribution":[{"species":"Plasmodium falciparum","strain":"3D7"}]},{"year":2022,"claim":"Live-cell tracking showed RhopH3 is discharged into the parasitophorous vacuole and only assembles the channel after export, revealing spatial control that prevents premature channel formation.","evidence":"Live-cell and super-resolution imaging, immunofluorescence, conditional knockdown and nutrient uptake assays in P. falciparum 3D7","pmids":["35393572"],"confidence":"High","gaps":["Export machinery requirements for RhopH3 not fully defined here","Signal timing assembly relative to phosphorylation not integrated"],"attribution":[{"species":"Plasmodium falciparum","strain":"3D7"}]},{"year":2026,"claim":"Testing the P. vivax homologue extended RhopH3 erythrocyte-binding function across species, mapping binding to specific recombinant regions.","evidence":"Recombinant region expression with immunoprecipitation and rosette-formation binding assays in P. vivax","pmids":["42314857"],"confidence":"Medium","gaps":["Host receptor for PvRhopH3 not identified","Functional invasion role in P. vivax not tested"],"attribution":[{"species":"Plasmodium vivax","strain":""}]},{"year":null,"claim":"It remains unresolved whether RhopH3 contributes structurally to the conductive PSAC pore itself or acts solely as an assembly/trafficking-essential subunit, and how S804 phosphorylation and disulfide-gated conformational change mechanistically drive discharge and membrane insertion.","evidence":"","pmids":[],"confidence":"High","gaps":["No membrane-inserted channel structure","Direct kinase-substrate proof for PfCDPK1-RhopH3 lacking","Molecular basis of RhopH3's unique non-redundancy versus CLAG3 unknown"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]}],"mechanism_profile":{"molecular_activity":[],"localization":[],"pathway":[],"complexes":["RhopH complex (CLAG3 : RhopH2 : RhopH3, 1:1:1) [#16, #17]","Merozoite invasion assembly with MSP-1(42), RhopH1, RAP-1, RAP-2, MSP-3/6/7/9 [#7]","Ternary complex RhopH3-MSP1(19)-band 3 5ABC [#9]","Host receptor complex: Cyclophilin B, Basigin, RhopH3, PfRh5 [#13]"],"partners":["CLAG3 (RHOPH1) [#2, #12, #16, #17]","RHOPH2 [#2, #12, #16, #17, #19]","RAMA (CO-LOCALIZATION) [#4]","HUMAN ERYTHROCYTE BAND 3 (5ABC REGION) [#9]","MSP1(19) [#9]","HUMAN CYCLOPHILIN B [#13]","PFALBA1 (RHOPH3 MRNA BINDING) [#8]","PFCDPK1 (CANDIDATE KINASE) [#14]","EXPORTED PROTEIN PF3D7_1401200 AND CYTOSKELETAL/MAURER'S CLEFT PARTNERS [#18]"],"other_free_text":["Essential gene; rhoph3 knockout not viable [#11, #15].","Uniquely required for PSAC/new permeability pathway nutrient uptake, unlike clag3 which is dispensable under standard conditions [#15].","110 kDa form processed to 105 kDa via C-terminal proteolysis [#3].","Phosphorylated at serine 804, gating rhoptry localization and discharge; critical for invasion but not intraerythrocytic development [#14].","Discharged into the parasitophorous vacuole separately from CLAG3, then exported to erythrocyte cytoplasm where the channel assembles [#19].","P. vivax homologue PvRhopH3 binds erythrocytes via regions R1 and R3 [#20]."]}},"prefetch_data":{},"corpus_meta":[{"pmid":"25080477","id":"PMC_25080477","title":"New antigens for a multicomponent blood-stage malaria vaccine.","date":"2014","source":"Science translational 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mini-exons, lacking tandem repeats, and containing B cell epitopes that induce antibody responses during natural infection.\",\n      \"method\": \"cDNA/genomic cloning, Western blotting, immunoelectron microscopy\",\n      \"journal\": \"Molecular and biochemical parasitology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Western blotting and immunoelectron microscopy establishing rhoptry localization, single lab with two orthogonal methods\",\n      \"pmids\": [\"1775161\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 1993,\n      \"finding\": \"During rhoptry biogenesis in P. falciparum, RhopH3 (as Rhop-H3) is first detectable in small granular low-density vesicle compartments (~1.12 g/ml sucrose) at the four-nucleus stage together with RhopH2, then later appears in higher-density mature rhoptries (~1.16 g/ml) at the 16-nucleus stage; RhopH3 mRNA peaks at the 8-nucleus stage, demonstrating stage-specific expression coordinated with rhoptry biogenesis.\",\n      \"method\": \"Subcellular fractionation, sucrose gradient centrifugation, immunoelectron microscopy, Northern blotting\",\n      \"journal\": \"Molecular and biochemical parasitology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods (fractionation, IEM, Northern blot) in single lab establishing trafficking sequence\",\n      \"pmids\": [\"8433718\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 1994,\n      \"finding\": \"Monoclonal antibodies recognizing the RhopH complex immunoprecipitated RhopH3 together with RhopH1 and RhopH2, confirming RhopH3 is a non-covalently associated component of the high molecular weight rhoptry complex; some mAbs recognized RhopH3 alone while others co-precipitated RhopH3 with RhopH1 or RhopH2, indicating distinct epitope accessibility.\",\n      \"method\": \"Immunoprecipitation, immunofluorescence, immunoelectron microscopy\",\n      \"journal\": \"Parasitology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — immunoprecipitation across 21 monoclonal antibodies providing convergent evidence for complex membership, single lab\",\n      \"pmids\": [\"7517517\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"Two major monoclonal antibody binding sites on RhopH3 were mapped to amino acids 823–828 (TDNTY/TDNTYK) and ~residue 850 of the C-terminal region. Antibodies to the ~850 site reacted exclusively with the 110 kDa form of RhopH3 but not the 105 kDa form, providing evidence that the 105 kDa RhopH3 polypeptide is generated from the 110 kDa form by C-terminal proteolytic processing.\",\n      \"method\": \"Overlapping peptide scanning, systematic amino acid replacement, Western blotting with isoform-specific antisera\",\n      \"journal\": \"Molecular and biochemical parasitology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — systematic peptide mapping combined with isoform-specific antisera, single lab but multiple orthogonal approaches\",\n      \"pmids\": [\"9106189\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"RhopH3 and RAP1 were found in close apposition with RAMA in early vesicles/pre-rhoptries, suggesting direct protein-protein interactions; this co-localization was disrupted by brefeldin A, implicating RAMA in trafficking RhopH3 into rhoptries via the Golgi-vesicle pathway.\",\n      \"method\": \"Immunofluorescence microscopy, brefeldin A inhibition, immunoelectron microscopy\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — co-localization-based inference of interaction, no direct pull-down for RhopH3 specifically, single lab\",\n      \"pmids\": [\"14613941\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"After red blood cell invasion by P. falciparum, the merozoite-acquired RhopH complex (including RhopH3) is transferred not only to the parasitophorous vacuole membrane but also to defined domains of the red blood cell cytoplasm, with possible transient association with Maurer's clefts.\",\n      \"method\": \"Immunofluorescence microscopy, subcellular fractionation of infected erythrocytes\",\n      \"journal\": \"Molecular and biochemical parasitology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — immunofluorescence and fractionation providing concordant subcellular localization data, single lab\",\n      \"pmids\": [\"18508137\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Fourteen synthetic peptides derived from RhopH3 (PF3D7_0905400) bound to human erythrocytes with saturable kinetics and nanomolar dissociation constants; binding was partially sensitive to sialic acid removal and glycoprotein-disrupting enzyme treatments. These peptides inhibited P. falciparum merozoite invasion of erythrocytes by up to 90% at 200 µM.\",\n      \"method\": \"Synthetic peptide erythrocyte binding assays, enzyme-treated erythrocytes, cross-linking assays, circular dichroism, invasion inhibition assays\",\n      \"journal\": \"Protein science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal binding and functional assays in single lab establishing erythrocyte-binding regions\",\n      \"pmids\": [\"18593818\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Proteomic pull-down experiments with anti-PfMSP-1 and anti-PfRhopH3 antibodies from merozoite lysates identified a complex containing PfRhopH3, PfMSP-1(42), PfRhopH1, PfRAP-1, PfRAP-2, MSP-3, MSP-6, MSP-7, and MSP-9, present at schizont/merozoite stages but not ring stage. Anti-PfRhopH3 antibodies blocked erythrocyte invasion.\",\n      \"method\": \"Co-immunoprecipitation / pull-down, tandem mass spectrometry, invasion inhibition assay\",\n      \"journal\": \"Journal of proteome research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — reciprocal pulldown with MS identification and functional invasion inhibition, single lab\",\n      \"pmids\": [\"21175202\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"The RNA-binding protein PfAlba1 binds RhopH3 mRNA in trophozoites and represses its translation at this stage; release of the mRNA from PfAlba1 complex in mature schizonts correlates with protein synthesis, establishing post-transcriptional translational timing control of RhopH3 expression.\",\n      \"method\": \"RNA immunoprecipitation with deep sequencing, ribosome occupancy, mRNA steady-state level analysis, epitope-tagged overexpression\",\n      \"journal\": \"Genome biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — RIP-seq plus translational profiling providing mechanistic evidence, single lab with multiple orthogonal methods\",\n      \"pmids\": [\"26415947\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"A direct biochemical interaction between RhopH3 and human erythrocyte band 3 (specifically the 5ABC extracellular region) was established by yeast two-hybrid screen and confirmed biochemically. RhopH3 forms a ternary complex with MSP1(19) and band 3 5ABC, and a recombinant segment of RhopH3 inhibited P. falciparum invasion of erythrocytes, implicating this interaction in the sialic acid-independent invasion pathway.\",\n      \"method\": \"Yeast two-hybrid, co-immunoprecipitation, recombinant protein invasion inhibition assay, anti-peptide antibody inhibition assay\",\n      \"journal\": \"Biochimica et biophysica acta\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — yeast two-hybrid plus biochemical co-IP plus functional inhibition, single lab with multiple orthogonal methods\",\n      \"pmids\": [\"25157665\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"3D7\"}]\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Conditional knockdown of RhopH3 in P. falciparum substantially reduces erythrocyte invasion capacity. Parasites that do invade despite RhopH3 knockdown show defective nutrient import (new permeability pathway / PSAC activity) and die. Knockdown of RhopH3 also disrupts the entire RhopH complex, interfering with organellar targeting and subsequent trafficking of all complex members.\",\n      \"method\": \"Conditional knockdown (DiCre-based truncation), invasion assays, sorbitol/nutrient uptake assays, immunofluorescence, Western blotting\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — conditional genetic knockdown with specific invasion, nutrient uptake, and complex assembly phenotypes, replicated across two independent labs (PMIDs 28252384 and 28221136)\",\n      \"pmids\": [\"28252384\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"3D7\"}]\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Conditional knockdown of RhopH3 in P. falciparum disrupts the entire RhopH complex assembly, interfering with organellar (rhoptry) targeting; knockdown abolishes nutrient channel (PSAC) activity; rhoph3 gene knockout was not viable, confirming RhopH3 is essential. RhopH3 contributes to erythrocyte invasion either through ligand-receptor interactions or subsequent parasite internalization steps.\",\n      \"method\": \"Conditional knockdown, gene knockout attempt, nutrient uptake assays, protein trafficking assays\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — conditional knockdown plus failed knockout plus functional channel assays, independently replicating findings from PMID 28252384\",\n      \"pmids\": [\"28221136\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"RhopH3 interacts with RhopH2, RhopH1, the erythrocyte cytoskeleton, and exported proteins involved in host cell remodeling, as shown by co-immunoprecipitation in the context of investigating the RhopH complex. Knockdown of RhopH2 (which depletes the RhopH2–RhopH3 interaction) leads to reduced nutrient and cofactor uptake and decreased pyrimidine synthesis.\",\n      \"method\": \"Co-immunoprecipitation, conditional knockdown of RhopH2, metabolomics, growth assays\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — co-IP establishing interaction partners of RhopH3, with functional metabolic readout from RhopH2 knockdown affecting the complex, single lab\",\n      \"pmids\": [\"28252383\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"3D7\"}]\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Human Cyclophilin B (present on erythrocyte surface) acts as a receptor for RhopH3 (PF3D7_0905400) during merozoite invasion. RhopH3 binds to red blood cells, and Cyclosporin A treatment (blocking Cyclophilin B) prevents merozoite invasion. A multi-protein complex involving Cyclophilin B, Basigin, RhopH3, and PfRh5 was identified.\",\n      \"method\": \"Localization and binding studies, co-immunoprecipitation, invasion inhibition with Cyclosporin A and peptide CDP3\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — co-IP and functional inhibition data, single lab, multiple orthogonal approaches but no reconstitution\",\n      \"pmids\": [\"29146974\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"RhopH3 is phosphorylated at serine 804 (S804) in P. falciparum parasites. CRISPR-Cas9 mutation of S804 to alanine (phosphomutant R3_S804A) demonstrated that this phosphorylation is critical for RBC invasion but not intraerythrocytic development. S804 phosphorylation regulates RhopH3 localization to rhoptries and its discharge from the parasite. PfCDPK1 was identified as a candidate kinase responsible for RhopH3-S804 phosphorylation, and it regulates RhopH3 secretion.\",\n      \"method\": \"CRISPR-Cas9 phosphomutant generation, invasion assays, immunofluorescence localization, kinase candidate identification\",\n      \"journal\": \"mBio\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — CRISPR-based active-site mutagenesis establishing phosphorylation-dependent localization and function, single lab with multiple orthogonal readouts\",\n      \"pmids\": [\"33024030\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"3D7\"}]\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"rhoph3 cannot be disrupted (knockout not viable) in P. falciparum because nutrient uptake is abolished in its absence, in contrast to clag3 which can be knocked out without abolishing transport under standard conditions. This establishes RhopH3 as uniquely essential for PSAC/NPP activity.\",\n      \"method\": \"Gene knockout attempts, sorbitol/nutrient uptake assays, genetic cross linkage analysis\",\n      \"journal\": \"PLoS pathogens\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — failed knockout combined with functional channel assays, replicating essentiality finding from multiple independent labs\",\n      \"pmids\": [\"32069335\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Cryo-EM structure of the native soluble RhopH trafficking complex at 2.9 Å resolution reveals RhopH3 forms large binding interfaces with CLAG3.1 but makes minimal direct contact with RhopH2. The complex assembles with 1:1:1 stoichiometry (CLAG3:RhopH2:RhopH3). RhopH3 contributes to stabilization via extensive disulfide bonding (contributing to 13 intramolecular disulfide bonds across the complex). Predicted transmembrane helices of CLAG3 are shielded within the soluble complex core.\",\n      \"method\": \"Single-particle cryo-EM (2.9 Å), mass spectrometry, cryoID structural determination of endogenous complex\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — atomic-resolution cryo-EM structure of the endogenous complex, confirmed by MS stoichiometry, two independent structural studies (PMIDs 33393463 and 34446549)\",\n      \"pmids\": [\"33393463\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Cryo-EM structure of the native RhopH complex shows CLAG3.1 is positioned centrally between RhopH2 and RhopH3, with RhopH3 sharing a substantial binding interface with CLAG3.1. RhopH3 stabilization involves intramolecular disulfide bonds; 13 disulfide bonds total stabilize the complex. The putative CLAG3 transmembrane helix (residues 1210–1223) is buried in a helical bundle, suggesting that membrane insertion requires a large conformational rearrangement, possibly triggered by allosteric disulfide bond breakage.\",\n      \"method\": \"Cryo-EM structure determination, mass spectrometry, cryoID program for subunit identification\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — independent atomic-resolution cryo-EM structure of native complex confirming RhopH3 binding interfaces, replicating PMID 33393463\",\n      \"pmids\": [\"34446549\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Five exported proteins (including the most strongly associated PF3D7_1401200) interact with all members of the RhopH complex (CLAG3, RhopH2, RhopH3) as shown by reciprocal immunoprecipitation, but conditional knockdown of these proteins had no effect on NPP/sorbitol uptake activity. Additional protein complexes (cytoskeletal and Maurer's cleft/J-dot complexes) associated with RhopH3-containing complex were identified by MS proteomics.\",\n      \"method\": \"Reciprocal co-immunoprecipitation, conditional knockdown, sorbitol/NPP uptake assay, mass spectrometry proteomics\",\n      \"journal\": \"Cellular microbiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — reciprocal co-IP and mass spectrometry identifying RhopH3 interaction partners in exported context, single lab\",\n      \"pmids\": [\"33774908\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"3D7\"}]\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"During merozoite invasion, RhopH3 and RhopH2 are released into the nascent parasitophorous vacuole (not directly into the host cell cytoplasm as CLAG3 is), and the full RhopH complex has not yet formed at this point. Export of RhopH2 and RhopH3 from the parasitophorous vacuole into the erythrocyte cytoplasm enables assembly of CLAG3/RhopH2/RhopH3 complexes and their incorporation into the host cell membrane, coinciding with activation of nutrient uptake. This compartmentalization prevents premature channel assembly.\",\n      \"method\": \"Live-cell imaging, immunofluorescence, conditional knockdown, nutrient uptake assays, super-resolution microscopy\",\n      \"journal\": \"Communications biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal imaging and functional methods establishing distinct trafficking routes and sequential assembly, single lab but rigorous\",\n      \"pmids\": [\"35393572\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"3D7\"}]\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"In P. vivax, the RhopH3 homologue (PvRhopH3) binds human erythrocytes; three expressed recombinant regions (R1, R2, R3) were tested and regions R1 and R3 showed erythrocyte binding capability by immunoprecipitation and rosette-formation assays, with R1 having the highest binding rates.\",\n      \"method\": \"Recombinant protein expression, immunoprecipitation, rosette-formation erythrocyte binding assay\",\n      \"journal\": \"Acta tropica\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — two orthogonal binding assays (co-IP and rosette assay) identifying erythrocyte-binding regions, single lab\",\n      \"pmids\": [\"42314857\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium vivax\", \"strain\": \"\"}]\n    }\n  ],\n  \"current_model\": \"RhopH3 (PF3D7_0905400) is an essential ~105–110 kDa rhoptry protein that assembles as a 1:1:1 soluble complex with CLAG3 and RhopH2 (the RhopH complex), whose cryo-EM structure shows RhopH3 forms large interfaces exclusively with CLAG3; during invasion RhopH3 is discharged into the parasitophorous vacuole (separately from CLAG3), then exported through the PTEX translocon into the erythrocyte cytoplasm where it assembles with CLAG3 and RhopH2 and inserts into the erythrocyte membrane to form the plasmodial surface anion channel (PSAC/NPP) essential for nutrient uptake; RhopH3 also contributes directly to erythrocyte invasion through interactions with host receptors including band 3 and Cyclophilin B; its localization to rhoptries and discharge competence are regulated by phosphorylation at serine 804, likely by PfCDPK1; and its mRNA translation timing is controlled by the RNA-binding protein PfAlba1.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"RhopH3 (PF3D7_0905400) is an essential rhoptry protein of P. falciparum that is indispensable both for erythrocyte invasion and for establishing the nutrient-uptake channel of the infected red cell [#0, #10, #11]. It assembles non-covalently with CLAG3 and RhopH2 into the high molecular weight RhopH complex [#2, #16], and cryo-EM of the native soluble complex resolves its architecture at atomic resolution: RhopH3 forms a large binding interface with CLAG3 while making minimal direct contact with RhopH2, and contributes to the extensive intramolecular disulfide bonding that shields CLAG3's putative transmembrane helix within the complex core [#16, #17]. RhopH3 is required for correct rhoptry targeting and trafficking of the entire complex, and its conditional knockdown both reduces invasion and abolishes new-permeability-pathway/PSAC activity in parasites that do invade; unlike clag3, rhoph3 cannot be deleted, marking it as uniquely essential for channel function [#10, #11, #15]. During invasion RhopH3 and RhopH2 are discharged into the nascent parasitophorous vacuole rather than directly into the host cytoplasm, and only after export into the erythrocyte does the CLAG3/RhopH2/RhopH3 channel assemble and activate nutrient uptake, a compartmentalization that prevents premature channel formation [#19]. RhopH3 also engages host determinants directly, binding erythrocyte band 3 (5ABC region) as part of a ternary complex with MSP1(19) in the sialic-acid-independent invasion pathway [#9] and using surface Cyclophilin B as a receptor [#13]. Its function is gated by phosphorylation at serine 804, which controls rhoptry localization and discharge and is critical for invasion, with PfCDPK1 identified as the candidate kinase [#14], while its translation timing is repressed post-transcriptionally by the RNA-binding protein PfAlba1 until schizogony [#8].\",\n  \"teleology\": [\n    {\n      \"year\": 1991,\n      \"claim\": \"Establishing that RhopH3 is a defined rhoptry protein created the molecular entity on which all subsequent invasion and channel work would build.\",\n      \"evidence\": \"cDNA/genomic cloning with Western blotting and immunoelectron microscopy in P. falciparum merozoites\",\n      \"pmids\": [\"1775161\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No function assigned at identification\", \"Relationship to other rhoptry proteins not yet defined\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 1993,\n      \"claim\": \"Tracking RhopH3 through rhoptry biogenesis showed its expression and trafficking are stage-coordinated with organelle maturation, framing it as a regulated rhoptry cargo.\",\n      \"evidence\": \"Subcellular fractionation, sucrose gradients, immunoelectron microscopy and Northern blotting across nuclear division stages\",\n      \"pmids\": [\"8433718\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Trafficking signals not identified\", \"Mechanism coordinating mRNA and protein timing unknown at this stage\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 1994,\n      \"claim\": \"Immunoprecipitation resolved whether RhopH3 acts alone or in a complex, defining it as a non-covalent member of the high molecular weight rhoptry complex.\",\n      \"evidence\": \"Immunoprecipitation with a panel of monoclonal antibodies plus immunofluorescence/immuno-EM\",\n      \"pmids\": [\"7517517\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Stoichiometry and binding interfaces undefined\", \"Functional consequence of complex membership unknown\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 1997,\n      \"claim\": \"Epitope mapping distinguished a 110 kDa precursor from a 105 kDa product, establishing that RhopH3 undergoes C-terminal proteolytic processing.\",\n      \"evidence\": \"Overlapping peptide scanning and isoform-specific antisera by Western blotting\",\n      \"pmids\": [\"9106189\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Protease responsible not identified\", \"Functional role of processing not determined\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Co-localization with RAMA implicated the Golgi-vesicle pathway in delivering RhopH3 to rhoptries, addressing how the protein reaches its organelle.\",\n      \"evidence\": \"Immunofluorescence, brefeldin A inhibition and immuno-EM in P. falciparum\",\n      \"pmids\": [\"14613941\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Co-localization inference without direct RhopH3 pull-down\", \"Direct RAMA-RhopH3 interaction not demonstrated\", \"Single lab\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Peptide-binding and invasion-inhibition experiments provided the first evidence that RhopH3 engages the erythrocyte surface during invasion.\",\n      \"evidence\": \"Synthetic peptide erythrocyte-binding assays with enzyme-treated cells and invasion inhibition in P. falciparum\",\n      \"pmids\": [\"18593818\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Erythrocyte receptor not identified at this stage\", \"Peptide binding may not reflect native protein geometry\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Following the RhopH complex after invasion revealed transfer beyond the parasite into the erythrocyte cytoplasm, foreshadowing a host-cell role for RhopH3.\",\n      \"evidence\": \"Immunofluorescence and subcellular fractionation of infected erythrocytes\",\n      \"pmids\": [\"18508137\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Export mechanism undefined\", \"Functional consequence in host cytoplasm not yet linked to nutrient transport\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Reciprocal pull-downs placed RhopH3 in a broader merozoite invasion assembly and showed anti-RhopH3 antibodies block invasion, functionally implicating it in RBC entry.\",\n      \"evidence\": \"Co-immunoprecipitation with tandem MS and invasion inhibition from merozoite lysates\",\n      \"pmids\": [\"21175202\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct versus indirect associations not resolved\", \"Which interactions are functionally required unclear\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Identifying band 3 as a direct RhopH3 ligand gave a molecular receptor for its sialic-acid-independent invasion role.\",\n      \"evidence\": \"Yeast two-hybrid, co-IP, ternary complex reconstitution and recombinant-protein invasion inhibition\",\n      \"pmids\": [\"25157665\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Binding region on RhopH3 not mapped to atomic detail\", \"Relative contribution versus other receptors unquantified\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"3D7\"}]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"RIP-seq and translational profiling explained how RhopH3 protein appears only at the right stage, identifying PfAlba1-mediated translational repression.\",\n      \"evidence\": \"RNA immunoprecipitation-seq, ribosome occupancy and mRNA level analysis with tagged overexpression\",\n      \"pmids\": [\"26415947\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Signal releasing the mRNA in schizonts unknown\", \"Direct PfAlba1 binding site on RhopH3 mRNA not mapped\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Conditional knockdown and failed knockout established RhopH3 as essential, required for complex assembly/trafficking, invasion, and PSAC-mediated nutrient uptake.\",\n      \"evidence\": \"DiCre conditional knockdown, knockout attempts, invasion assays, sorbitol/nutrient uptake and trafficking readouts across two independent labs\",\n      \"pmids\": [\"28252384\", \"28221136\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Separating invasion role from channel role at the molecular level incomplete\", \"Whether RhopH3 forms channel pore directly unknown\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"3D7\"}]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Co-IP tied RhopH3 to RhopH2, RhopH1, host cytoskeleton and exported remodeling proteins, and metabolic assays linked complex integrity to nutrient/cofactor uptake and pyrimidine synthesis.\",\n      \"evidence\": \"Co-immunoprecipitation with conditional RhopH2 knockdown, metabolomics and growth assays\",\n      \"pmids\": [\"28252383\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Metabolic phenotype driven via RhopH2 knockdown rather than RhopH3 directly\", \"Direct cytoskeleton contacts of RhopH3 not resolved\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"3D7\"}]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Identifying erythrocyte-surface Cyclophilin B as a RhopH3 receptor added a second host determinant and placed RhopH3 in a receptor complex with Basigin and PfRh5.\",\n      \"evidence\": \"Localization/binding studies, co-IP and invasion inhibition with Cyclosporin A and peptide CDP3\",\n      \"pmids\": [\"29146974\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct versus complex-mediated RhopH3-Cyclophilin B binding not fully separated\", \"No reconstitution of the receptor complex\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Phosphomutant analysis showed S804 phosphorylation gates RhopH3 rhoptry localization and discharge and is critical for invasion, naming PfCDPK1 as candidate kinase.\",\n      \"evidence\": \"CRISPR-Cas9 S804A mutant, invasion assays, immunofluorescence localization and kinase candidate identification in P. falciparum 3D7\",\n      \"pmids\": [\"33024030\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct PfCDPK1 phosphorylation of RhopH3 not biochemically proven\", \"How phosphorylation mechanistically controls discharge unresolved\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"3D7\"}]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Comparing rhoph3 with clag3 showed only RhopH3 is strictly required for nutrient uptake, defining its unique essentiality for PSAC/NPP activity.\",\n      \"evidence\": \"Knockout attempts, sorbitol/nutrient uptake assays and genetic cross linkage analysis\",\n      \"pmids\": [\"32069335\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular basis of RhopH3's non-redundant role in the channel undefined\", \"Whether RhopH3 contributes to conductive pathway itself unknown\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Cryo-EM structures of the native soluble complex resolved RhopH3's architecture, showing it interfaces largely with CLAG3, minimally with RhopH2, and helps shield CLAG3's transmembrane helix via disulfide bonding.\",\n      \"evidence\": \"Single-particle cryo-EM at 2.9 A with MS stoichiometry and cryoID, two independent structural studies\",\n      \"pmids\": [\"33393463\", \"34446549\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Membrane-inserted channel conformation not captured\", \"Trigger for the conformational change to membrane insertion unresolved\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Reciprocal IP defined exported and cytoskeletal/Maurer's cleft partners of the RhopH3 complex, but their knockdown left NPP activity intact, distinguishing associated proteins from channel-essential ones.\",\n      \"evidence\": \"Reciprocal co-IP, conditional knockdown, sorbitol/NPP uptake assay and MS proteomics in P. falciparum 3D7\",\n      \"pmids\": [\"33774908\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional role of the exported partners undefined\", \"Direct binding to RhopH3 versus other complex members not resolved\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"3D7\"}]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Live-cell tracking showed RhopH3 is discharged into the parasitophorous vacuole and only assembles the channel after export, revealing spatial control that prevents premature channel formation.\",\n      \"evidence\": \"Live-cell and super-resolution imaging, immunofluorescence, conditional knockdown and nutrient uptake assays in P. falciparum 3D7\",\n      \"pmids\": [\"35393572\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Export machinery requirements for RhopH3 not fully defined here\", \"Signal timing assembly relative to phosphorylation not integrated\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"3D7\"}]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Testing the P. vivax homologue extended RhopH3 erythrocyte-binding function across species, mapping binding to specific recombinant regions.\",\n      \"evidence\": \"Recombinant region expression with immunoprecipitation and rosette-formation binding assays in P. vivax\",\n      \"pmids\": [\"42314857\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Host receptor for PvRhopH3 not identified\", \"Functional invasion role in P. vivax not tested\"],\n      \"attribution\": [{\"species\": \"Plasmodium vivax\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"It remains unresolved whether RhopH3 contributes structurally to the conductive PSAC pore itself or acts solely as an assembly/trafficking-essential subunit, and how S804 phosphorylation and disulfide-gated conformational change mechanistically drive discharge and membrane insertion.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No membrane-inserted channel structure\", \"Direct kinase-substrate proof for PfCDPK1-RhopH3 lacking\", \"Molecular basis of RhopH3's unique non-redundancy versus CLAG3 unknown\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0005102\", \"supporting_discovery_ids\": [6, 9, 13, 20]},\n      {\"term_id\": \"GO:0005198\", \"supporting_discovery_ids\": [16, 17]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0020008\", \"supporting_discovery_ids\": [0, 1, 4, 14]},\n      {\"term_id\": \"GO:0005811\", \"supporting_discovery_ids\": [16, 17]},\n      {\"term_id\": \"GO:0020003\", \"supporting_discovery_ids\": [5, 19]},\n      {\"term_id\": \"GO:0020036\", \"supporting_discovery_ids\": [5, 18]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0044409\", \"supporting_discovery_ids\": [6, 9, 10, 13]},\n      {\"term_id\": \"GO:0015893\", \"supporting_discovery_ids\": [10, 11, 12, 15, 19]},\n      {\"term_id\": \"GO:0006417\", \"supporting_discovery_ids\": [8]}\n    ],\n    \"complexes\": [\n      \"RhopH complex (CLAG3 : RhopH2 : RhopH3, 1:1:1) [#16, #17]\",\n      \"Merozoite invasion assembly with MSP-1(42), RhopH1, RAP-1, RAP-2, MSP-3/6/7/9 [#7]\",\n      \"Ternary complex RhopH3-MSP1(19)-band 3 5ABC [#9]\",\n      \"Host receptor complex: Cyclophilin B, Basigin, RhopH3, PfRh5 [#13]\"\n    ],\n    \"partners\": [\n      \"CLAG3 (RhopH1) [#2, #12, #16, #17]\",\n      \"RhopH2 [#2, #12, #16, #17, #19]\",\n      \"RAMA (co-localization) [#4]\",\n      \"Human erythrocyte band 3 (5ABC region) [#9]\",\n      \"MSP1(19) [#9]\",\n      \"Human Cyclophilin B [#13]\",\n      \"PfAlba1 (RhopH3 mRNA binding) [#8]\",\n      \"PfCDPK1 (candidate kinase) [#14]\",\n      \"Exported protein PF3D7_1401200 and cytoskeletal/Maurer's cleft partners [#18]\"\n    ],\n    \"other_free_text\": [\n      \"Essential gene; rhoph3 knockout not viable [#11, #15].\",\n      \"Uniquely required for PSAC/new permeability pathway nutrient uptake, unlike clag3 which is dispensable under standard conditions [#15].\",\n      \"110 kDa form processed to 105 kDa via C-terminal proteolysis [#3].\",\n      \"Phosphorylated at serine 804, gating rhoptry localization and discharge; critical for invasion but not intraerythrocytic development [#14].\",\n      \"Discharged into the parasitophorous vacuole separately from CLAG3, then exported to erythrocyte cytoplasm where the channel assembles [#19].\",\n      \"P. vivax homologue PvRhopH3 binds erythrocytes via regions R1 and R3 [#20].\"\n    ]\n  }\n}","audit_flag":null,"strains":[{"strain":"Pf3D7","gene_id":"PF3D7_0905400","name":null,"product":"high molecular weight rhoptry protein 3","uniprot_acc":null,"chromosome":null,"start_pos":null},{"strain":"PbANKA","gene_id":"PBANKA_0416000","name":null,"product":"high molecular weight rhoptry protein 3, putative","uniprot_acc":null,"chromosome":null,"start_pos":null},{"strain":"PkH","gene_id":"PKNH_0703100","name":null,"product":"high molecular weight rhoptry protein 3, putative","uniprot_acc":null,"chromosome":null,"start_pos":null}],"gene_symbol":"RhopH3","evaluation":null}