{"gene":"PF3D7_0930300","run_date":"2026-09-08T12:51:27","timeline":{"discoveries":[{"year":1990,"finding":"During erythrocyte invasion by P. falciparum merozoites, only a small C-terminal fragment of the MSP1 precursor complex is retained on the parasite surface and carried into the newly infected red cell; antibodies to this fragment inhibit invasion.","method":"Biochemical fractionation of merozoite surface proteins combined with antibody invasion-inhibition assays","journal":"The Journal of experimental medicine","confidence":"High","confidence_rationale":"Tier 2 / Strong — direct biochemical identification of the retained fragment with functional antibody inhibition assay; independently replicated by multiple subsequent studies","pmids":["1694225"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":1985,"finding":"MSP1 (P195) is synthesized as a ~195 kDa precursor that is proteolytically processed into three major merozoite surface fragments of ~83 kDa, ~42 kDa, and ~19 kDa; the complete gene structure was determined from cDNA and genomic DNA clones.","method":"Molecular cloning and sequencing of cDNA and genomic DNA; protein biochemistry","journal":"Nature","confidence":"High","confidence_rationale":"Tier 1 / Strong — complete primary structure determined from multiple DNA clones, independently confirmed across many subsequent studies","pmids":["2995820"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":1991,"finding":"The C-terminal fragment of MSP1 that is carried into the red cell during invasion consists of two epidermal growth factor (EGF)-like domains; N-terminal amino acid sequencing of fragments defined their position in the precursor. The smaller fragment is not N-glycosylated. A homologous cleavage sequence and EGF-like domain structure is found in MSP1 of other Plasmodium species.","method":"N-terminal amino acid sequencing of purified fragments; comparison with predicted gene sequence; glycosylation analysis","journal":"Molecular and biochemical parasitology","confidence":"High","confidence_rationale":"Tier 1 / Strong — direct N-terminal sequencing establishing domain structure, replicated in multiple follow-up structural studies","pmids":["1775158"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":"T9/94"}]},{"year":1996,"finding":"MSP1 is anchored in the merozoite membrane via a glycosylphosphatidylinositol (GPI) anchor; detailed structural analysis showed the GPI anchor contains an extra α1-2 linked mannose at the conserved trimannosyl core glycan and carries primarily myristic acid at the inositol ring with palmitic acid in ester linkage on diacylglycerol.","method":"Metabolic labeling with tritiated precursors; enzymatic and chemical treatments; structural analysis of released GPI anchor fragments","journal":"Molecular and biochemical parasitology","confidence":"High","confidence_rationale":"Tier 1 / Strong — direct biochemical structural characterization of GPI anchor with multiple orthogonal chemical/enzymatic methods","pmids":["8992312"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":1997,"finding":"Monoclonal antibodies that inhibit MSP1 secondary processing and erythrocyte invasion are blocked by naturally acquired human antibodies specific for epitopes within the N-terminal 83 kDa domain of MSP1, completely abrogating the invasion-inhibitory effect; blocking antibodies compete with processing-inhibitory antibodies for binding to MSP1(19) epitopes on the merozoite surface.","method":"Quantitative antibody-mediated inhibition assays; competitive binding assays; affinity-purified human antibodies tested in invasion inhibition and MSP1 secondary processing assays in vitro","journal":"The Journal of experimental medicine","confidence":"High","confidence_rationale":"Tier 2 / Strong — direct functional assays with purified antibodies, multiple orthogonal approaches (processing inhibition + invasion inhibition + competitive binding), replicated finding","pmids":["9362529"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":1999,"finding":"The solution structure of the 96-residue C-terminal MSP1(19) fragment was determined by NMR; it comprises two EGF-like domains with a novel U-shaped interdomain interface formed by a hydrophobic residue cluster, placing the N-terminal proteolytic processing site close to the C-terminal GPI anchor site, consistent with a membrane-bound proteinase mediating processing during erythrocyte invasion. Epitopes for invasion-inhibitory and blocking antibodies were mapped onto the 3D structure.","method":"NMR spectroscopy on uniformly 13C/15N-labelled recombinant protein expressed in Pichia pastoris; structure determination and epitope mapping","journal":"Journal of molecular biology","confidence":"High","confidence_rationale":"Tier 1 / Strong — full solution structure by NMR with functional epitope mapping; independent validation by crystal structure in 2003","pmids":["10339410"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2003,"finding":"The crystal structure of recombinant P. falciparum MSP1(19) in complex with the Fab fragment of monoclonal antibody G17.12 was determined; G17.12 recognizes a discontinuous epitope of 13 residues on the first EGF-like domain of MSP1(19). G17.12 binds uniformly to the surface of merozoites from late schizont stage but does not inhibit erythrocyte invasion or MSP1 processing.","method":"X-ray crystallography of MSP1(19)-Fab complex; immunofluorescence on intact merozoites; invasion inhibition assay","journal":"Journal of molecular biology","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structure with functional validation; negative invasion-inhibition result explicitly documented","pmids":["12729744"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2001,"finding":"Epitopes for invasion-inhibitory mAbs 12.8 and 12.10 and blocking mAbs 1E1 and 7.5 on MSP1(19) were mapped by site-directed mutagenesis (26 individual amino acid changes) and PEPSCAN analysis; inhibitory epitopes are conformational and primarily within the first EGF-like domain; incorporation of specific amino acid changes enabled design of proteins that bound inhibitory but not blocking antibodies.","method":"Site-directed mutagenesis; PEPSCAN; Western blotting; BIAcore binding analysis; 3D structural mapping","journal":"Journal of molecular biology","confidence":"High","confidence_rationale":"Tier 1 / Strong — extensive mutagenesis (26 mutants) combined with multiple orthogonal binding assays and structural mapping","pmids":["11292349"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2003,"finding":"Two nonglycosylated exofacial regions of erythrocyte band 3 (termed 5ABC and 6A) serve as host receptors binding the C-terminal processing products of MSP1. Native MSP1(42) and recombinant MSP1(19) both bound 5ABC; MSP1(42) also bound intact RBCs; binding was sialic acid-independent but chymotrypsin-sensitive. Band 3-derived peptides and soluble 5ABC inhibited P. falciparum invasion of RBCs in vitro.","method":"Pulldown binding assays with recombinant MSP1 fragments and band 3 peptides; neuraminidase and chymotrypsin treatment of RBCs; in vitro invasion inhibition assays","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 / Strong — direct binding assays with native and recombinant proteins plus functional inhibition, multiple orthogonal methods","pmids":["12692305"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2003,"finding":"MSP1(42) and MSP9 (ABRA) form a stable co-ligand complex that together targets erythrocyte band 3 receptor (5ABC) during invasion; MSP9 also binds 5ABC and intact erythrocytes independently, and soluble 5ABC blocks MSP9-erythrocyte binding.","method":"Co-immunoprecipitation; pulldown binding assays with recombinant MSP9 polypeptides; invasion inhibition assays","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal binding assays with native and recombinant proteins; single lab, multiple orthogonal methods","pmids":["14630931"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2005,"finding":"PfSUB2, an integral membrane subtilisin-like protease stored in micronemes, is the merozoite surface 'sheddase' responsible for shedding MSP1 ectodomain components during erythrocyte invasion. PfSUB2 is secreted onto the parasite surface upon merozoite release and translocates to the posterior pole in an actin-dependent manner. The recombinant PfSUB2 propeptide binds specifically to mature parasite-derived PfSUB2 and potently and selectively inhibits MSP1 (and AMA1) shedding.","method":"Molecular identification of PfSUB2; propeptide binding assay (pulldown); selective inhibition of MSP1 shedding in parasite cultures; actin inhibitor treatment; immunolocalization","journal":"PLoS pathogens","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (localization, selective propeptide inhibition, actin-dependence, direct binding) in a single rigorous study","pmids":["16322767"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2009,"finding":"PfSUB1, a subtilisin-like protease discharged into the parasitophorous vacuole, proteolytically matures MSP1 (as well as MSP6 and MSP7) on the merozoite surface just before egress. Inhibition of PfSUB1 activity results in accumulation of unprocessed MSP1 on the merozoite surface and significantly reduces erythrocyte invasion.","method":"PfSUB1 inhibitor treatment of P. falciparum cultures; Western blot analysis of MSP1 processing; invasion assay","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 2 / Strong — pharmacological inhibition of PfSUB1 with direct biochemical read-out of MSP1 processing status and functional invasion assay; multiple orthogonal methods","pmids":["19214190"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2009,"finding":"MSP1 is expressed during liver-stage as well as blood-stage schizogony in P. berghei. Conditional silencing of MSP1 in sporozoites using a Flp/FRT recombination system impaired subsequent merozoite formation in the liver, demonstrating a dual role for MSP1 in both liver-stage and erythrocytic-stage parasite development.","method":"Flp/FRT conditional gene silencing in P. berghei; sporozoite-stage promoter-driven excision; liver-stage development assay","journal":"Cell host & microbe","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean conditional knockout with specific developmental stage phenotype, direct functional consequence measured","pmids":["19380117"],"is_preprint":false,"attribution":[{"species":"Plasmodium berghei","strain":""}]},{"year":2010,"finding":"MSP1(42), a processed form of MSP1 involved in invasion, binds heparin-like molecules in a specific manner; MSP1(33) also binds heparin, but MSP1(19) does not. Optimal heparin binding and invasion inhibition required a degree of sulfation ≥2, disulfation of N-acetylglucosamine or hexuronic acid, and a minimum chain length of 6 monosaccharides.","method":"Heparin-binding assays with native MSP1(42) and recombinant fragments; real-time imaging of invasion inhibition; structure-activity analysis of heparin variants","journal":"Blood","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct binding assay with native protein plus functional invasion inhibition; single lab","pmids":["20220119"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2015,"finding":"SUB1-mediated proteolytic processing of MSP1 modifies its secondary structure and activates its capacity to bind spectrin, the major component of the erythrocyte cytoskeleton. Parasites expressing an inefficiently processed MSP1 mutant showed delayed egress, and merozoites lacking surface-bound MSP1 displayed a severe egress defect, indicating that processed MSP1 facilitates host erythrocyte rupture for parasite egress.","method":"MSP1 processing mutant parasites; spectrin-binding assays; live egress imaging; genetic knock-down/displacement of surface MSP1; secondary structure analysis","journal":"Cell host & microbe","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods including mutant parasites, direct binding assay, live imaging, and loss-of-function with specific egress phenotype in a single study","pmids":["26468747"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2015,"finding":"The amino-terminus of MSP1 directly interacts with human erythrocyte glycophorin A (GPA). Phage display mapping identified the binding domain; this region of MSP1 potently inhibits P. falciparum invasion of RBCs. A genetically modified mouse model lacking the GPA-band 3 complex in RBCs was completely resistant to malaria infection in vivo, indicating an essential role of the MSP1-GPA-band 3 complex in initial adhesion during invasion.","method":"Phage display technology; recombinant protein binding assays; GPA-band 3 knockout mouse model; in vivo infection challenge","journal":"Blood","confidence":"High","confidence_rationale":"Tier 2 / Strong — phage display identification plus knockout mouse model providing in vivo functional validation; multiple orthogonal methods","pmids":["25778531"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2001,"finding":"MSP6 (36 kDa) is non-covalently associated with the MSP1 complex on the merozoite surface. MSP6(36) was co-immunoprecipitated with MSP1 from parasite culture supernatant. MSP6(36) is also found in a form not bound to MSP1. The C-terminal region of MSP6 may be involved in binding to MSP1 subunit p38.","method":"N-terminal sequencing; mass spectrometry; co-immunoprecipitation from culture supernatant; immunofluorescence; gene cloning","journal":"Molecular and biochemical parasitology","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — single Co-IP identifying MSP6 as complex member; confirmed by MS and immunofluorescence in same study","pmids":["11166390"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2006,"finding":"Using heterologously produced recombinant proteins, MSP6(36) and MSP7 each bind independently to MSP1. MSP6(36) contacts only the p38 subunit of MSP1, while MSP7 interacts with p83, p30, and p38. The intact C-terminal region of MSP6 is required for association with p38 and for MSP6 multimerization into tetramers. Only the processed (not precursor) form of MSP1 interacts with MSP6(36).","method":"In vitro binding assays with recombinant MSP1 subunits, MSP6, and MSP7; deletion/truncation analysis of MSP6; analytical ultracentrifugation for multimerization","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro reconstitution of complex with recombinant proteins plus domain mapping; single lab, multiple orthogonal biochemical methods","pmids":["16940297"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2016,"finding":"MSP3, MSP6, MSPDBL1, MSPDBL2, and MSP7 each bind directly to MSP1, but independently of each other, forming multiple distinct MSP1 complex forms on the parasite surface. These MSP1 complexes have overlapping functions and interact directly with human erythrocytes. Inhibitory antibodies targeting the p83 fragment of MSP1 inhibit all forms of MSP1 complexes and disrupt parasite growth in vitro.","method":"Direct binding assays between recombinant proteins; erythrocyte binding assays; parasite growth inhibition with anti-p83 antibodies","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — systematic direct binding assays across multiple ligand combinations, erythrocyte-binding functional assay, and antibody inhibition; multiple orthogonal methods","pmids":["26823464"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2008,"finding":"After merozoite invasion, MSP1(19) persists intact throughout the intraerythrocytic cycle and is the first marker for food vacuole biogenesis. MSP1(19) is rapidly endocytosed into small vacuoles in the ring stage, which coalesce to form the single food vacuole containing hemozoin; it persists in the residual body. MSP1(19) and the chloroquine resistance transporter (CRT) are both components of the food vacuole membrane. Newly synthesized MSP1 is excluded from the vacuole.","method":"Metabolic labeling of MSP1(19); fluorescence live imaging; immuno-electron microscopy; immunochemical analysis of vacuole fractions","journal":"PloS one","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal localization methods (immunofluorescence, immuno-EM, metabolic labeling) tracking MSP1(19) fate through the intraerythrocytic cycle","pmids":["18769730"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":1994,"finding":"Recombinant MSP1(19) C-terminal EGF-like domain fragment expressed in yeast displays correct disulfide bond-dependent conformation; structural analysis showed a single amino acid change (E to Q) in the first EGF domain significantly alters conformation. Conserved and variant B-cell epitopes including known protective antibody targets were authentically recreated.","method":"Yeast expression and secretion of His-tagged recombinant MSP1(19) variants; direct and competitive ELISA; disulfide bond-dependent conformational analysis","journal":"Molecular and biochemical parasitology","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — single amino acid change affecting conformation demonstrated biochemically; single lab, two orthogonal assays","pmids":["7516493"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":1993,"finding":"Immunization of mice with a recombinant P. yoelii MSP1 protein containing only the two C-terminal EGF-like domains confers protection against lethal blood-stage challenge; reduction and alkylation of the protein (disrupting disulfide bonds) abolished protection, demonstrating an absolute requirement for the disulfide-bonded conformation for immunogenicity and protective efficacy.","method":"Recombinant protein immunization; chemical reduction and alkylation; lethal blood-stage challenge model in mice","journal":"Parasite immunology","confidence":"High","confidence_rationale":"Tier 2 / Strong — direct chemical ablation experiment proving disulfide bond requirement, with in vivo protection readout","pmids":["8015856"],"is_preprint":false,"attribution":[{"species":"Plasmodium yoelii","strain":""}]}],"current_model":"P. falciparum MSP1 (PF3D7_0930300) is synthesized as a ~195 kDa GPI-anchored precursor that is proteolytically processed by PfSUB1 into a non-covalent surface complex (p83/p30/p38/p42) just before egress; PfSUB2 then sheds the ectodomain during erythrocyte invasion, retaining only the C-terminal MSP1(19) fragment (two EGF-like domains in a U-shaped structure, requiring intact disulfide bonds) on the merozoite; the processed MSP1 complex binds erythrocytes via its N-terminus to glycophorin A and via MSP1(42)/MSP1(19) to band 3, and the SUB1-activated form additionally binds spectrin to facilitate host cell rupture during egress; MSP6 (binding p38), MSP7 (binding p83/p30/p38), and other peripheral proteins form multiple independent MSP1 complexes on the merozoite surface, while after invasion MSP1(19) is internalized to mark the biogenesis of the food vacuole."},"narrative":{"mechanistic_narrative":"MSP1 (PF3D7_0930300) is the principal GPI-anchored surface protein of the Plasmodium merozoite and functions as a stage-transiting adhesin that mediates both host erythrocyte rupture during egress and initial attachment during invasion [PMID:2995820, PMID:26468747, PMID:25778531]. It is synthesized as a ~195 kDa precursor that is proteolytically matured into a non-covalent surface complex of ~83, ~42, and ~19 kDa fragments [PMID:2995820], with the intact protein attached to the merozoite membrane through a structurally distinctive GPI anchor bearing an extra mannose and myristate/palmitate acylation [PMID:8992312]. Two sequential proteases act on MSP1: PfSUB1, discharged into the parasitophorous vacuole just before egress, matures the surface complex, and its inhibition leaves unprocessed MSP1 on the surface and blocks invasion [PMID:19214190]; the SUB1-processed form gains the capacity to bind erythrocyte spectrin, and parasites with inefficiently processed or surface-depleted MSP1 show severe egress defects, establishing that processed MSP1 drives host cell rupture [PMID:26468747]. During the subsequent invasion, the micronemal sheddase PfSUB2 removes the ectodomain, retaining only the C-terminal MSP1(19) fragment on the parasite [PMID:16322767]. MSP1 engages host receptors through distinct regions: the N-terminus binds glycophorin A, whose GPA-band 3 complex is essential for infection in vivo [PMID:25778531], while the C-terminal MSP1(42)/MSP1(19) products bind nonglycosylated exofacial regions of erythrocyte band 3 [PMID:12692305]; MSP1(42) additionally binds heparin-like molecules [PMID:20220119]. The retained MSP1(19) fragment is a compact two-EGF-domain module with a U-shaped interdomain interface stabilized by disulfide bonds, structurally positioning the N-terminal processing site near the GPI anchor and carrying the epitopes of invasion-inhibitory antibodies [PMID:10339410, PMID:1775158]; its disulfide-bonded conformation is absolutely required for protective immunogenicity [PMID:8015856]. On the merozoite surface, MSP1 nucleates multiple independent complexes by binding peripheral partners including MSP6, MSP7, MSP3, MSPDBL1, and MSPDBL2 (MSP6 contacting the p38 subunit and MSP7 contacting p83/p30/p38), all of which contribute to erythrocyte binding [PMID:11166390, PMID:16940297, PMID:26823464]. Beyond blood-stage invasion, MSP1 also functions in liver-stage development, where conditional silencing in P. berghei impairs hepatic merozoite formation [PMID:19380117], and after invasion MSP1(19) is internalized to mark food vacuole biogenesis [PMID:18769730].","teleology":[{"year":1985,"claim":"Establishing that MSP1 is a large precursor cleaved into defined fragments framed the entire model of a proteolytically matured surface protein.","evidence":"Molecular cloning and sequencing of cDNA/genomic DNA with protein biochemistry defining the ~195 kDa precursor and its ~83/~42/~19 kDa products","pmids":["2995820"],"confidence":"High","gaps":["Did not identify the proteases responsible for processing","Did not establish receptor-binding function of the fragments"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":1990,"claim":"Showing that only a small C-terminal fragment is carried into the new red cell and that antibodies to it block invasion pinpointed MSP1(19) as the functionally critical invasion moiety.","evidence":"Biochemical fractionation of merozoite surface proteins combined with antibody invasion-inhibition assays","pmids":["1694225"],"confidence":"High","gaps":["Mechanism by which the fragment supports invasion was unresolved","Host receptor unknown at this point"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":1991,"claim":"Defining the C-terminal fragment as two EGF-like domains and locating fragment boundaries by N-terminal sequencing established the domain architecture of the retained module.","evidence":"N-terminal amino acid sequencing of purified fragments compared with predicted gene sequence; glycosylation analysis","pmids":["1775158"],"confidence":"High","gaps":["3D fold not yet determined","Functional role of the EGF domains unproven"],"attribution":[{"species":"Plasmodium falciparum","strain":"T9/94"}]},{"year":1993,"claim":"Immunization with disulfide-bonded C-terminal EGF domains conferred protection that was abolished by reduction/alkylation, proving the conformation is essential for protective immunity.","evidence":"Recombinant P. yoelii MSP1 immunization with chemical reduction/alkylation and lethal blood-stage challenge in mice","pmids":["8015856"],"confidence":"High","gaps":["Shown in P. yoelii, not P. falciparum","Does not define the protective epitopes at residue level"],"attribution":[{"species":"Plasmodium yoelii","strain":""}]},{"year":1996,"claim":"Characterizing the GPI anchor established how MSP1 is tethered to the merozoite membrane, a prerequisite for surface retention and shedding.","evidence":"Metabolic labeling and enzymatic/chemical structural analysis of the released GPI anchor","pmids":["8992312"],"confidence":"High","gaps":["Did not address the sheddase that releases the ectodomain","Functional consequence of the atypical acylation not tested"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":1999,"claim":"Solving the MSP1(19) solution structure revealed a U-shaped two-EGF module placing the processing site near the GPI anchor and mapped inhibitory/blocking antibody epitopes onto the fold.","evidence":"NMR spectroscopy of 13C/15N-labelled recombinant protein with epitope mapping","pmids":["10339410"],"confidence":"High","gaps":["Structure of the full processed complex not resolved","Receptor-binding surface not yet mapped"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2001,"claim":"Fine mutagenesis and PEPSCAN localized conformational invasion-inhibitory epitopes to the first EGF domain and enabled design of proteins discriminating inhibitory from blocking antibodies, clarifying the antigenic determinants relevant to vaccine design.","evidence":"Site-directed mutagenesis (26 mutants), PEPSCAN, BIAcore, and 3D structural mapping","pmids":["11292349"],"confidence":"High","gaps":["Does not establish the natural receptor contacts of these residues","Blocking-antibody interference mechanism not fully resolved"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2001,"claim":"Identifying MSP6 as a non-covalent partner of MSP1 opened the concept that MSP1 organizes accessory surface proteins into a complex.","evidence":"Co-immunoprecipitation from culture supernatant with N-terminal sequencing, MS, and immunofluorescence","pmids":["11166390"],"confidence":"Medium","gaps":["Single Co-IP; binding subunit inferred not directly mapped","Fraction of MSP6 unbound to MSP1 unexplained"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":1994,"claim":"Demonstrating disulfide-dependent authentic folding of recombinant MSP1(19) in yeast, and that a single E-to-Q change alters conformation, established requirements for producing correctly folded antigen.","evidence":"Yeast expression of MSP1(19) variants with direct/competitive ELISA and conformational analysis","pmids":["7516493"],"confidence":"Medium","gaps":["Two-assay single-lab characterization","In vivo protective consequence of the E-to-Q change not tested"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2003,"claim":"Identifying erythrocyte band 3 regions 5ABC and 6A as receptors for the C-terminal MSP1 products defined the host-binding function of MSP1(42)/MSP1(19).","evidence":"Pulldown binding assays with recombinant fragments and band 3 peptides, enzymatic RBC treatments, and invasion inhibition","pmids":["12692305"],"confidence":"High","gaps":["Affinity and stoichiometry of the interaction not quantified","Relationship to the N-terminal GPA interaction unresolved at this stage"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2003,"claim":"Showing MSP1(42) and MSP9 form a co-ligand complex targeting band 3 extended the invasion adhesion model to multi-protein receptor engagement.","evidence":"Co-immunoprecipitation, pulldown binding assays with recombinant MSP9, and invasion inhibition","pmids":["14630931"],"confidence":"Medium","gaps":["Single lab; in vivo requirement of the co-complex not tested","Whether MSP9 binds MSP1 directly or via band 3 not fully separated"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2003,"claim":"A crystal structure of MSP1(19) with a non-inhibitory Fab distinguished antibody binding from functional inhibition, showing surface binding alone does not block invasion.","evidence":"X-ray crystallography of MSP1(19)-Fab complex, immunofluorescence, and invasion inhibition assay","pmids":["12729744"],"confidence":"High","gaps":["Does not explain why some epitopes inhibit and others do not mechanistically"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2005,"claim":"Identifying PfSUB2 as the micronemal sheddase that removes the MSP1 ectodomain during invasion defined the enzyme responsible for retaining only MSP1(19).","evidence":"Molecular identification, propeptide binding/inhibition, actin-dependence, and immunolocalization","pmids":["16322767"],"confidence":"High","gaps":["Exact MSP1 cleavage site by PfSUB2 not defined here","Consequence of blocking shedding on invasion kinetics not fully quantified"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2006,"claim":"Reconstituting MSP6 and MSP7 binding to specific MSP1 subunits with recombinant proteins mapped the architecture of the surface complex and showed only processed MSP1 binds MSP6.","evidence":"In vitro binding with recombinant MSP1 subunits, MSP6, and MSP7, deletion analysis, and analytical ultracentrifugation","pmids":["16940297"],"confidence":"High","gaps":["In vitro reconstitution; native surface stoichiometry not measured","Functional role of MSP6 multimerization unresolved"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2008,"claim":"Tracking MSP1(19) after invasion showed it is internalized and marks food vacuole biogenesis, revealing a post-invasion fate distinct from its surface role.","evidence":"Metabolic labeling, live fluorescence imaging, immuno-EM, and vacuole fractionation","pmids":["18769730"],"confidence":"High","gaps":["Functional contribution of MSP1(19) to food vacuole formation not established","Mechanism of endocytic uptake unknown"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2009,"claim":"Establishing PfSUB1 as the pre-egress protease that matures MSP1 completed the two-protease processing scheme and linked processing to invasion competence.","evidence":"PfSUB1 inhibitor treatment with Western blot of MSP1 processing and invasion assays","pmids":["19214190"],"confidence":"High","gaps":["Direct enzyme-substrate reconstitution not shown here","Contribution of MSP6/MSP7 co-processing to invasion not dissected"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2009,"claim":"Conditional silencing in P. berghei revealed MSP1 is required for liver-stage merozoite formation, extending its role beyond the blood stage.","evidence":"Flp/FRT conditional gene silencing in sporozoites with liver-stage development assays","pmids":["19380117"],"confidence":"High","gaps":["Shown in P. berghei, not P. falciparum","Molecular function of MSP1 in the liver stage undefined"],"attribution":[{"species":"Plasmodium berghei","strain":""}]},{"year":2010,"claim":"Demonstrating that MSP1(42) and MSP1(33), but not MSP1(19), bind sulfated heparin-like molecules identified an additional carbohydrate interaction relevant to invasion inhibition.","evidence":"Heparin-binding assays with native and recombinant fragments and real-time invasion imaging","pmids":["20220119"],"confidence":"Medium","gaps":["Single lab; physiological heparan sulfate ligand on RBCs not identified","Relationship to band 3/GPA binding unresolved"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2015,"claim":"Showing that SUB1 processing activates spectrin binding and that MSP1 loss/impaired processing causes egress defects reframed MSP1 as an active mediator of host cell rupture, not merely an invasion adhesin.","evidence":"MSP1 processing mutants, spectrin-binding assays, live egress imaging, and surface-MSP1 displacement with secondary structure analysis","pmids":["26468747"],"confidence":"High","gaps":["How spectrin binding mechanically destabilizes the membrane not defined","Whether partner proteins modulate spectrin binding untested"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2015,"claim":"Identifying the MSP1 N-terminus as a glycophorin A binding domain and showing GPA-band 3 knockout mice resist malaria established the in vivo essentiality of the MSP1-GPA-band 3 adhesion axis.","evidence":"Phage display mapping, recombinant binding assays, GPA-band 3 knockout mouse model, and in vivo infection challenge","pmids":["25778531"],"confidence":"High","gaps":["Mouse model reports the receptor complex, not direct MSP1 gene knockout in vivo","Sequential order of GPA vs band 3 engagement not resolved"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2016,"claim":"Systematic reconstitution showed MSP3, MSP6, MSPDBL1, MSPDBL2, and MSP7 each bind MSP1 independently to form multiple overlapping erythrocyte-binding complexes, and anti-p83 antibodies inhibit all forms, defining MSP1 as a hub organizing redundant surface complexes.","evidence":"Direct recombinant binding assays, erythrocyte binding assays, and growth inhibition with anti-p83 antibodies","pmids":["26823464"],"confidence":"High","gaps":["Relative abundance of each complex form on the native surface not quantified","Functional redundancy not tested by combined gene disruption"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":null,"claim":"How the processed MSP1 complex 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antibodies to this fragment inhibit invasion.\",\n      \"method\": \"Biochemical fractionation of merozoite surface proteins combined with antibody invasion-inhibition assays\",\n      \"journal\": \"The Journal of experimental medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — direct biochemical identification of the retained fragment with functional antibody inhibition assay; independently replicated by multiple subsequent studies\",\n      \"pmids\": [\"1694225\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 1985,\n      \"finding\": \"MSP1 (P195) is synthesized as a ~195 kDa precursor that is proteolytically processed into three major merozoite surface fragments of ~83 kDa, ~42 kDa, and ~19 kDa; the complete gene structure was determined from cDNA and genomic DNA clones.\",\n      \"method\": \"Molecular cloning and sequencing of cDNA and genomic DNA; protein biochemistry\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — complete primary structure determined from multiple DNA clones, independently confirmed across many subsequent studies\",\n      \"pmids\": [\"2995820\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 1991,\n      \"finding\": \"The C-terminal fragment of MSP1 that is carried into the red cell during invasion consists of two epidermal growth factor (EGF)-like domains; N-terminal amino acid sequencing of fragments defined their position in the precursor. The smaller fragment is not N-glycosylated. A homologous cleavage sequence and EGF-like domain structure is found in MSP1 of other Plasmodium species.\",\n      \"method\": \"N-terminal amino acid sequencing of purified fragments; comparison with predicted gene sequence; glycosylation analysis\",\n      \"journal\": \"Molecular and biochemical parasitology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — direct N-terminal sequencing establishing domain structure, replicated in multiple follow-up structural studies\",\n      \"pmids\": [\"1775158\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"T9/94\"}]\n    },\n    {\n      \"year\": 1996,\n      \"finding\": \"MSP1 is anchored in the merozoite membrane via a glycosylphosphatidylinositol (GPI) anchor; detailed structural analysis showed the GPI anchor contains an extra α1-2 linked mannose at the conserved trimannosyl core glycan and carries primarily myristic acid at the inositol ring with palmitic acid in ester linkage on diacylglycerol.\",\n      \"method\": \"Metabolic labeling with tritiated precursors; enzymatic and chemical treatments; structural analysis of released GPI anchor fragments\",\n      \"journal\": \"Molecular and biochemical parasitology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — direct biochemical structural characterization of GPI anchor with multiple orthogonal chemical/enzymatic methods\",\n      \"pmids\": [\"8992312\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"Monoclonal antibodies that inhibit MSP1 secondary processing and erythrocyte invasion are blocked by naturally acquired human antibodies specific for epitopes within the N-terminal 83 kDa domain of MSP1, completely abrogating the invasion-inhibitory effect; blocking antibodies compete with processing-inhibitory antibodies for binding to MSP1(19) epitopes on the merozoite surface.\",\n      \"method\": \"Quantitative antibody-mediated inhibition assays; competitive binding assays; affinity-purified human antibodies tested in invasion inhibition and MSP1 secondary processing assays in vitro\",\n      \"journal\": \"The Journal of experimental medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — direct functional assays with purified antibodies, multiple orthogonal approaches (processing inhibition + invasion inhibition + competitive binding), replicated finding\",\n      \"pmids\": [\"9362529\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"The solution structure of the 96-residue C-terminal MSP1(19) fragment was determined by NMR; it comprises two EGF-like domains with a novel U-shaped interdomain interface formed by a hydrophobic residue cluster, placing the N-terminal proteolytic processing site close to the C-terminal GPI anchor site, consistent with a membrane-bound proteinase mediating processing during erythrocyte invasion. Epitopes for invasion-inhibitory and blocking antibodies were mapped onto the 3D structure.\",\n      \"method\": \"NMR spectroscopy on uniformly 13C/15N-labelled recombinant protein expressed in Pichia pastoris; structure determination and epitope mapping\",\n      \"journal\": \"Journal of molecular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — full solution structure by NMR with functional epitope mapping; independent validation by crystal structure in 2003\",\n      \"pmids\": [\"10339410\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"The crystal structure of recombinant P. falciparum MSP1(19) in complex with the Fab fragment of monoclonal antibody G17.12 was determined; G17.12 recognizes a discontinuous epitope of 13 residues on the first EGF-like domain of MSP1(19). G17.12 binds uniformly to the surface of merozoites from late schizont stage but does not inhibit erythrocyte invasion or MSP1 processing.\",\n      \"method\": \"X-ray crystallography of MSP1(19)-Fab complex; immunofluorescence on intact merozoites; invasion inhibition assay\",\n      \"journal\": \"Journal of molecular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structure with functional validation; negative invasion-inhibition result explicitly documented\",\n      \"pmids\": [\"12729744\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"Epitopes for invasion-inhibitory mAbs 12.8 and 12.10 and blocking mAbs 1E1 and 7.5 on MSP1(19) were mapped by site-directed mutagenesis (26 individual amino acid changes) and PEPSCAN analysis; inhibitory epitopes are conformational and primarily within the first EGF-like domain; incorporation of specific amino acid changes enabled design of proteins that bound inhibitory but not blocking antibodies.\",\n      \"method\": \"Site-directed mutagenesis; PEPSCAN; Western blotting; BIAcore binding analysis; 3D structural mapping\",\n      \"journal\": \"Journal of molecular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — extensive mutagenesis (26 mutants) combined with multiple orthogonal binding assays and structural mapping\",\n      \"pmids\": [\"11292349\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Two nonglycosylated exofacial regions of erythrocyte band 3 (termed 5ABC and 6A) serve as host receptors binding the C-terminal processing products of MSP1. Native MSP1(42) and recombinant MSP1(19) both bound 5ABC; MSP1(42) also bound intact RBCs; binding was sialic acid-independent but chymotrypsin-sensitive. Band 3-derived peptides and soluble 5ABC inhibited P. falciparum invasion of RBCs in vitro.\",\n      \"method\": \"Pulldown binding assays with recombinant MSP1 fragments and band 3 peptides; neuraminidase and chymotrypsin treatment of RBCs; in vitro invasion inhibition assays\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — direct binding assays with native and recombinant proteins plus functional inhibition, multiple orthogonal methods\",\n      \"pmids\": [\"12692305\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"MSP1(42) and MSP9 (ABRA) form a stable co-ligand complex that together targets erythrocyte band 3 receptor (5ABC) during invasion; MSP9 also binds 5ABC and intact erythrocytes independently, and soluble 5ABC blocks MSP9-erythrocyte binding.\",\n      \"method\": \"Co-immunoprecipitation; pulldown binding assays with recombinant MSP9 polypeptides; invasion inhibition assays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal binding assays with native and recombinant proteins; single lab, multiple orthogonal methods\",\n      \"pmids\": [\"14630931\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"PfSUB2, an integral membrane subtilisin-like protease stored in micronemes, is the merozoite surface 'sheddase' responsible for shedding MSP1 ectodomain components during erythrocyte invasion. PfSUB2 is secreted onto the parasite surface upon merozoite release and translocates to the posterior pole in an actin-dependent manner. The recombinant PfSUB2 propeptide binds specifically to mature parasite-derived PfSUB2 and potently and selectively inhibits MSP1 (and AMA1) shedding.\",\n      \"method\": \"Molecular identification of PfSUB2; propeptide binding assay (pulldown); selective inhibition of MSP1 shedding in parasite cultures; actin inhibitor treatment; immunolocalization\",\n      \"journal\": \"PLoS pathogens\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (localization, selective propeptide inhibition, actin-dependence, direct binding) in a single rigorous study\",\n      \"pmids\": [\"16322767\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"PfSUB1, a subtilisin-like protease discharged into the parasitophorous vacuole, proteolytically matures MSP1 (as well as MSP6 and MSP7) on the merozoite surface just before egress. Inhibition of PfSUB1 activity results in accumulation of unprocessed MSP1 on the merozoite surface and significantly reduces erythrocyte invasion.\",\n      \"method\": \"PfSUB1 inhibitor treatment of P. falciparum cultures; Western blot analysis of MSP1 processing; invasion assay\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — pharmacological inhibition of PfSUB1 with direct biochemical read-out of MSP1 processing status and functional invasion assay; multiple orthogonal methods\",\n      \"pmids\": [\"19214190\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"MSP1 is expressed during liver-stage as well as blood-stage schizogony in P. berghei. Conditional silencing of MSP1 in sporozoites using a Flp/FRT recombination system impaired subsequent merozoite formation in the liver, demonstrating a dual role for MSP1 in both liver-stage and erythrocytic-stage parasite development.\",\n      \"method\": \"Flp/FRT conditional gene silencing in P. berghei; sporozoite-stage promoter-driven excision; liver-stage development assay\",\n      \"journal\": \"Cell host & microbe\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean conditional knockout with specific developmental stage phenotype, direct functional consequence measured\",\n      \"pmids\": [\"19380117\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium berghei\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"MSP1(42), a processed form of MSP1 involved in invasion, binds heparin-like molecules in a specific manner; MSP1(33) also binds heparin, but MSP1(19) does not. Optimal heparin binding and invasion inhibition required a degree of sulfation ≥2, disulfation of N-acetylglucosamine or hexuronic acid, and a minimum chain length of 6 monosaccharides.\",\n      \"method\": \"Heparin-binding assays with native MSP1(42) and recombinant fragments; real-time imaging of invasion inhibition; structure-activity analysis of heparin variants\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct binding assay with native protein plus functional invasion inhibition; single lab\",\n      \"pmids\": [\"20220119\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"SUB1-mediated proteolytic processing of MSP1 modifies its secondary structure and activates its capacity to bind spectrin, the major component of the erythrocyte cytoskeleton. Parasites expressing an inefficiently processed MSP1 mutant showed delayed egress, and merozoites lacking surface-bound MSP1 displayed a severe egress defect, indicating that processed MSP1 facilitates host erythrocyte rupture for parasite egress.\",\n      \"method\": \"MSP1 processing mutant parasites; spectrin-binding assays; live egress imaging; genetic knock-down/displacement of surface MSP1; secondary structure analysis\",\n      \"journal\": \"Cell host & microbe\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods including mutant parasites, direct binding assay, live imaging, and loss-of-function with specific egress phenotype in a single study\",\n      \"pmids\": [\"26468747\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"The amino-terminus of MSP1 directly interacts with human erythrocyte glycophorin A (GPA). Phage display mapping identified the binding domain; this region of MSP1 potently inhibits P. falciparum invasion of RBCs. A genetically modified mouse model lacking the GPA-band 3 complex in RBCs was completely resistant to malaria infection in vivo, indicating an essential role of the MSP1-GPA-band 3 complex in initial adhesion during invasion.\",\n      \"method\": \"Phage display technology; recombinant protein binding assays; GPA-band 3 knockout mouse model; in vivo infection challenge\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — phage display identification plus knockout mouse model providing in vivo functional validation; multiple orthogonal methods\",\n      \"pmids\": [\"25778531\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"MSP6 (36 kDa) is non-covalently associated with the MSP1 complex on the merozoite surface. MSP6(36) was co-immunoprecipitated with MSP1 from parasite culture supernatant. MSP6(36) is also found in a form not bound to MSP1. The C-terminal region of MSP6 may be involved in binding to MSP1 subunit p38.\",\n      \"method\": \"N-terminal sequencing; mass spectrometry; co-immunoprecipitation from culture supernatant; immunofluorescence; gene cloning\",\n      \"journal\": \"Molecular and biochemical parasitology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — single Co-IP identifying MSP6 as complex member; confirmed by MS and immunofluorescence in same study\",\n      \"pmids\": [\"11166390\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Using heterologously produced recombinant proteins, MSP6(36) and MSP7 each bind independently to MSP1. MSP6(36) contacts only the p38 subunit of MSP1, while MSP7 interacts with p83, p30, and p38. The intact C-terminal region of MSP6 is required for association with p38 and for MSP6 multimerization into tetramers. Only the processed (not precursor) form of MSP1 interacts with MSP6(36).\",\n      \"method\": \"In vitro binding assays with recombinant MSP1 subunits, MSP6, and MSP7; deletion/truncation analysis of MSP6; analytical ultracentrifugation for multimerization\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro reconstitution of complex with recombinant proteins plus domain mapping; single lab, multiple orthogonal biochemical methods\",\n      \"pmids\": [\"16940297\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"MSP3, MSP6, MSPDBL1, MSPDBL2, and MSP7 each bind directly to MSP1, but independently of each other, forming multiple distinct MSP1 complex forms on the parasite surface. These MSP1 complexes have overlapping functions and interact directly with human erythrocytes. Inhibitory antibodies targeting the p83 fragment of MSP1 inhibit all forms of MSP1 complexes and disrupt parasite growth in vitro.\",\n      \"method\": \"Direct binding assays between recombinant proteins; erythrocyte binding assays; parasite growth inhibition with anti-p83 antibodies\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — systematic direct binding assays across multiple ligand combinations, erythrocyte-binding functional assay, and antibody inhibition; multiple orthogonal methods\",\n      \"pmids\": [\"26823464\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"After merozoite invasion, MSP1(19) persists intact throughout the intraerythrocytic cycle and is the first marker for food vacuole biogenesis. MSP1(19) is rapidly endocytosed into small vacuoles in the ring stage, which coalesce to form the single food vacuole containing hemozoin; it persists in the residual body. MSP1(19) and the chloroquine resistance transporter (CRT) are both components of the food vacuole membrane. Newly synthesized MSP1 is excluded from the vacuole.\",\n      \"method\": \"Metabolic labeling of MSP1(19); fluorescence live imaging; immuno-electron microscopy; immunochemical analysis of vacuole fractions\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal localization methods (immunofluorescence, immuno-EM, metabolic labeling) tracking MSP1(19) fate through the intraerythrocytic cycle\",\n      \"pmids\": [\"18769730\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 1994,\n      \"finding\": \"Recombinant MSP1(19) C-terminal EGF-like domain fragment expressed in yeast displays correct disulfide bond-dependent conformation; structural analysis showed a single amino acid change (E to Q) in the first EGF domain significantly alters conformation. Conserved and variant B-cell epitopes including known protective antibody targets were authentically recreated.\",\n      \"method\": \"Yeast expression and secretion of His-tagged recombinant MSP1(19) variants; direct and competitive ELISA; disulfide bond-dependent conformational analysis\",\n      \"journal\": \"Molecular and biochemical parasitology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — single amino acid change affecting conformation demonstrated biochemically; single lab, two orthogonal assays\",\n      \"pmids\": [\"7516493\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 1993,\n      \"finding\": \"Immunization of mice with a recombinant P. yoelii MSP1 protein containing only the two C-terminal EGF-like domains confers protection against lethal blood-stage challenge; reduction and alkylation of the protein (disrupting disulfide bonds) abolished protection, demonstrating an absolute requirement for the disulfide-bonded conformation for immunogenicity and protective efficacy.\",\n      \"method\": \"Recombinant protein immunization; chemical reduction and alkylation; lethal blood-stage challenge model in mice\",\n      \"journal\": \"Parasite immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — direct chemical ablation experiment proving disulfide bond requirement, with in vivo protection readout\",\n      \"pmids\": [\"8015856\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium yoelii\", \"strain\": \"\"}]\n    }\n  ],\n  \"current_model\": \"P. falciparum MSP1 (PF3D7_0930300) is synthesized as a ~195 kDa GPI-anchored precursor that is proteolytically processed by PfSUB1 into a non-covalent surface complex (p83/p30/p38/p42) just before egress; PfSUB2 then sheds the ectodomain during erythrocyte invasion, retaining only the C-terminal MSP1(19) fragment (two EGF-like domains in a U-shaped structure, requiring intact disulfide bonds) on the merozoite; the processed MSP1 complex binds erythrocytes via its N-terminus to glycophorin A and via MSP1(42)/MSP1(19) to band 3, and the SUB1-activated form additionally binds spectrin to facilitate host cell rupture during egress; MSP6 (binding p38), MSP7 (binding p83/p30/p38), and other peripheral proteins form multiple independent MSP1 complexes on the merozoite surface, while after invasion MSP1(19) is internalized to mark the biogenesis of the food vacuole.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"MSP1 (PF3D7_0930300) is the principal GPI-anchored surface protein of the Plasmodium merozoite and functions as a stage-transiting adhesin that mediates both host erythrocyte rupture during egress and initial attachment during invasion [#1, #14, #15]. It is synthesized as a ~195 kDa precursor that is proteolytically matured into a non-covalent surface complex of ~83, ~42, and ~19 kDa fragments [#1], with the intact protein attached to the merozoite membrane through a structurally distinctive GPI anchor bearing an extra mannose and myristate/palmitate acylation [#3]. Two sequential proteases act on MSP1: PfSUB1, discharged into the parasitophorous vacuole just before egress, matures the surface complex, and its inhibition leaves unprocessed MSP1 on the surface and blocks invasion [#11]; the SUB1-processed form gains the capacity to bind erythrocyte spectrin, and parasites with inefficiently processed or surface-depleted MSP1 show severe egress defects, establishing that processed MSP1 drives host cell rupture [#14]. During the subsequent invasion, the micronemal sheddase PfSUB2 removes the ectodomain, retaining only the C-terminal MSP1(19) fragment on the parasite [#10]. MSP1 engages host receptors through distinct regions: the N-terminus binds glycophorin A, whose GPA-band 3 complex is essential for infection in vivo [#15], while the C-terminal MSP1(42)/MSP1(19) products bind nonglycosylated exofacial regions of erythrocyte band 3 [#8]; MSP1(42) additionally binds heparin-like molecules [#13]. The retained MSP1(19) fragment is a compact two-EGF-domain module with a U-shaped interdomain interface stabilized by disulfide bonds, structurally positioning the N-terminal processing site near the GPI anchor and carrying the epitopes of invasion-inhibitory antibodies [#5, #2]; its disulfide-bonded conformation is absolutely required for protective immunogenicity [#21]. On the merozoite surface, MSP1 nucleates multiple independent complexes by binding peripheral partners including MSP6, MSP7, MSP3, MSPDBL1, and MSPDBL2 (MSP6 contacting the p38 subunit and MSP7 contacting p83/p30/p38), all of which contribute to erythrocyte binding [#16, #17, #18]. Beyond blood-stage invasion, MSP1 also functions in liver-stage development, where conditional silencing in P. berghei impairs hepatic merozoite formation [#12], and after invasion MSP1(19) is internalized to mark food vacuole biogenesis [#19].\",\n  \"teleology\": [\n    {\n      \"year\": 1985,\n      \"claim\": \"Establishing that MSP1 is a large precursor cleaved into defined fragments framed the entire model of a proteolytically matured surface protein.\",\n      \"evidence\": \"Molecular cloning and sequencing of cDNA/genomic DNA with protein biochemistry defining the ~195 kDa precursor and its ~83/~42/~19 kDa products\",\n      \"pmids\": [\"2995820\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not identify the proteases responsible for processing\", \"Did not establish receptor-binding function of the fragments\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 1990,\n      \"claim\": \"Showing that only a small C-terminal fragment is carried into the new red cell and that antibodies to it block invasion pinpointed MSP1(19) as the functionally critical invasion moiety.\",\n      \"evidence\": \"Biochemical fractionation of merozoite surface proteins combined with antibody invasion-inhibition assays\",\n      \"pmids\": [\"1694225\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism by which the fragment supports invasion was unresolved\", \"Host receptor unknown at this point\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 1991,\n      \"claim\": \"Defining the C-terminal fragment as two EGF-like domains and locating fragment boundaries by N-terminal sequencing established the domain architecture of the retained module.\",\n      \"evidence\": \"N-terminal amino acid sequencing of purified fragments compared with predicted gene sequence; glycosylation analysis\",\n      \"pmids\": [\"1775158\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"3D fold not yet determined\", \"Functional role of the EGF domains unproven\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"T9/94\"}]\n    },\n    {\n      \"year\": 1993,\n      \"claim\": \"Immunization with disulfide-bonded C-terminal EGF domains conferred protection that was abolished by reduction/alkylation, proving the conformation is essential for protective immunity.\",\n      \"evidence\": \"Recombinant P. yoelii MSP1 immunization with chemical reduction/alkylation and lethal blood-stage challenge in mice\",\n      \"pmids\": [\"8015856\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Shown in P. yoelii, not P. falciparum\", \"Does not define the protective epitopes at residue level\"],\n      \"attribution\": [{\"species\": \"Plasmodium yoelii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 1996,\n      \"claim\": \"Characterizing the GPI anchor established how MSP1 is tethered to the merozoite membrane, a prerequisite for surface retention and shedding.\",\n      \"evidence\": \"Metabolic labeling and enzymatic/chemical structural analysis of the released GPI anchor\",\n      \"pmids\": [\"8992312\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not address the sheddase that releases the ectodomain\", \"Functional consequence of the atypical acylation not tested\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 1999,\n      \"claim\": \"Solving the MSP1(19) solution structure revealed a U-shaped two-EGF module placing the processing site near the GPI anchor and mapped inhibitory/blocking antibody epitopes onto the fold.\",\n      \"evidence\": \"NMR spectroscopy of 13C/15N-labelled recombinant protein with epitope mapping\",\n      \"pmids\": [\"10339410\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structure of the full processed complex not resolved\", \"Receptor-binding surface not yet mapped\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"Fine mutagenesis and PEPSCAN localized conformational invasion-inhibitory epitopes to the first EGF domain and enabled design of proteins discriminating inhibitory from blocking antibodies, clarifying the antigenic determinants relevant to vaccine design.\",\n      \"evidence\": \"Site-directed mutagenesis (26 mutants), PEPSCAN, BIAcore, and 3D structural mapping\",\n      \"pmids\": [\"11292349\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Does not establish the natural receptor contacts of these residues\", \"Blocking-antibody interference mechanism not fully resolved\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"Identifying MSP6 as a non-covalent partner of MSP1 opened the concept that MSP1 organizes accessory surface proteins into a complex.\",\n      \"evidence\": \"Co-immunoprecipitation from culture supernatant with N-terminal sequencing, MS, and immunofluorescence\",\n      \"pmids\": [\"11166390\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single Co-IP; binding subunit inferred not directly mapped\", \"Fraction of MSP6 unbound to MSP1 unexplained\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 1994,\n      \"claim\": \"Demonstrating disulfide-dependent authentic folding of recombinant MSP1(19) in yeast, and that a single E-to-Q change alters conformation, established requirements for producing correctly folded antigen.\",\n      \"evidence\": \"Yeast expression of MSP1(19) variants with direct/competitive ELISA and conformational analysis\",\n      \"pmids\": [\"7516493\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Two-assay single-lab characterization\", \"In vivo protective consequence of the E-to-Q change not tested\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Identifying erythrocyte band 3 regions 5ABC and 6A as receptors for the C-terminal MSP1 products defined the host-binding function of MSP1(42)/MSP1(19).\",\n      \"evidence\": \"Pulldown binding assays with recombinant fragments and band 3 peptides, enzymatic RBC treatments, and invasion inhibition\",\n      \"pmids\": [\"12692305\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Affinity and stoichiometry of the interaction not quantified\", \"Relationship to the N-terminal GPA interaction unresolved at this stage\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Showing MSP1(42) and MSP9 form a co-ligand complex targeting band 3 extended the invasion adhesion model to multi-protein receptor engagement.\",\n      \"evidence\": \"Co-immunoprecipitation, pulldown binding assays with recombinant MSP9, and invasion inhibition\",\n      \"pmids\": [\"14630931\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab; in vivo requirement of the co-complex not tested\", \"Whether MSP9 binds MSP1 directly or via band 3 not fully separated\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"A crystal structure of MSP1(19) with a non-inhibitory Fab distinguished antibody binding from functional inhibition, showing surface binding alone does not block invasion.\",\n      \"evidence\": \"X-ray crystallography of MSP1(19)-Fab complex, immunofluorescence, and invasion inhibition assay\",\n      \"pmids\": [\"12729744\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Does not explain why some epitopes inhibit and others do not mechanistically\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Identifying PfSUB2 as the micronemal sheddase that removes the MSP1 ectodomain during invasion defined the enzyme responsible for retaining only MSP1(19).\",\n      \"evidence\": \"Molecular identification, propeptide binding/inhibition, actin-dependence, and immunolocalization\",\n      \"pmids\": [\"16322767\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Exact MSP1 cleavage site by PfSUB2 not defined here\", \"Consequence of blocking shedding on invasion kinetics not fully quantified\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Reconstituting MSP6 and MSP7 binding to specific MSP1 subunits with recombinant proteins mapped the architecture of the surface complex and showed only processed MSP1 binds MSP6.\",\n      \"evidence\": \"In vitro binding with recombinant MSP1 subunits, MSP6, and MSP7, deletion analysis, and analytical ultracentrifugation\",\n      \"pmids\": [\"16940297\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vitro reconstitution; native surface stoichiometry not measured\", \"Functional role of MSP6 multimerization unresolved\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Tracking MSP1(19) after invasion showed it is internalized and marks food vacuole biogenesis, revealing a post-invasion fate distinct from its surface role.\",\n      \"evidence\": \"Metabolic labeling, live fluorescence imaging, immuno-EM, and vacuole fractionation\",\n      \"pmids\": [\"18769730\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Functional contribution of MSP1(19) to food vacuole formation not established\", \"Mechanism of endocytic uptake unknown\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Establishing PfSUB1 as the pre-egress protease that matures MSP1 completed the two-protease processing scheme and linked processing to invasion competence.\",\n      \"evidence\": \"PfSUB1 inhibitor treatment with Western blot of MSP1 processing and invasion assays\",\n      \"pmids\": [\"19214190\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct enzyme-substrate reconstitution not shown here\", \"Contribution of MSP6/MSP7 co-processing to invasion not dissected\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Conditional silencing in P. berghei revealed MSP1 is required for liver-stage merozoite formation, extending its role beyond the blood stage.\",\n      \"evidence\": \"Flp/FRT conditional gene silencing in sporozoites with liver-stage development assays\",\n      \"pmids\": [\"19380117\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Shown in P. berghei, not P. falciparum\", \"Molecular function of MSP1 in the liver stage undefined\"],\n      \"attribution\": [{\"species\": \"Plasmodium berghei\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Demonstrating that MSP1(42) and MSP1(33), but not MSP1(19), bind sulfated heparin-like molecules identified an additional carbohydrate interaction relevant to invasion inhibition.\",\n      \"evidence\": \"Heparin-binding assays with native and recombinant fragments and real-time invasion imaging\",\n      \"pmids\": [\"20220119\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab; physiological heparan sulfate ligand on RBCs not identified\", \"Relationship to band 3/GPA binding unresolved\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Showing that SUB1 processing activates spectrin binding and that MSP1 loss/impaired processing causes egress defects reframed MSP1 as an active mediator of host cell rupture, not merely an invasion adhesin.\",\n      \"evidence\": \"MSP1 processing mutants, spectrin-binding assays, live egress imaging, and surface-MSP1 displacement with secondary structure analysis\",\n      \"pmids\": [\"26468747\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How spectrin binding mechanically destabilizes the membrane not defined\", \"Whether partner proteins modulate spectrin binding untested\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Identifying the MSP1 N-terminus as a glycophorin A binding domain and showing GPA-band 3 knockout mice resist malaria established the in vivo essentiality of the MSP1-GPA-band 3 adhesion axis.\",\n      \"evidence\": \"Phage display mapping, recombinant binding assays, GPA-band 3 knockout mouse model, and in vivo infection challenge\",\n      \"pmids\": [\"25778531\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mouse model reports the receptor complex, not direct MSP1 gene knockout in vivo\", \"Sequential order of GPA vs band 3 engagement not resolved\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Systematic reconstitution showed MSP3, MSP6, MSPDBL1, MSPDBL2, and MSP7 each bind MSP1 independently to form multiple overlapping erythrocyte-binding complexes, and anti-p83 antibodies inhibit all forms, defining MSP1 as a hub organizing redundant surface complexes.\",\n      \"evidence\": \"Direct recombinant binding assays, erythrocyte binding assays, and growth inhibition with anti-p83 antibodies\",\n      \"pmids\": [\"26823464\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Relative abundance of each complex form on the native surface not quantified\", \"Functional redundancy not tested by combined gene disruption\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How the processed MSP1 complex integrates its egress-promoting spectrin interaction with its multiple invasion-adhesion contacts (GPA, band 3, heparin) into a single ordered mechanochemical program, and the molecular function of MSP1 in the liver stage, remain unresolved.\",\n      \"evidence\": \"No timeline discovery reconciles the egress and invasion binding activities or defines liver-stage function at the molecular level\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No structure of the full processed complex bound to receptors\", \"Liver-stage molecular function of MSP1 undefined\", \"Order and coordination of GPA/band 3/spectrin engagement unknown\"],\n      \"attribution\": []\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0005515\", \"supporting_discovery_ids\": [16, 17, 18, 9]},\n      {\"term_id\": \"GO:0030246\", \"supporting_discovery_ids\": [13]},\n      {\"term_id\": \"GO:0046790\", \"supporting_discovery_ids\": [8, 15]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0009986\", \"supporting_discovery_ids\": [0, 1, 6, 18]},\n      {\"term_id\": \"GO:0046658\", \"supporting_discovery_ids\": [3]},\n      {\"term_id\": \"GO:0020020\", \"supporting_discovery_ids\": [19]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0044409\", \"supporting_discovery_ids\": [0, 8, 15]},\n      {\"term_id\": \"GO:0051673\", \"supporting_discovery_ids\": [14]},\n      {\"term_id\": \"GO:0016485\", \"supporting_discovery_ids\": [1, 10, 11]}\n    ],\n    \"complexes\": [\n      \"MSP1 processed surface complex (p83/p30/p38/p42/p19)\",\n      \"MSP1-MSP6 complex (MSP6 binds p38)\",\n      \"MSP1-MSP7 complex (MSP7 binds p83/p30/p38)\",\n      \"MSP1(42)-MSP9 co-ligand complex\",\n      \"MSP1-MSP3 / MSP1-MSPDBL1 / MSP1-MSPDBL2 complexes\"\n    ],\n    \"partners\": [\n      \"MSP6\",\n      \"MSP7\",\n      \"MSP3\",\n      \"MSPDBL1\",\n      \"MSPDBL2\",\n      \"MSP9 (ABRA)\",\n      \"PfSUB1 (maturation protease)\",\n      \"PfSUB2 (sheddase)\",\n      \"erythrocyte glycophorin A\",\n      \"erythrocyte band 3 (regions 5ABC and 6A)\",\n      \"erythrocyte spectrin\",\n      \"heparin-like molecules\"\n    ],\n    \"other_free_text\": [\n      \"Synthesized as a ~195 kDa GPI-anchored precursor processed into ~83, ~42, and ~19 kDa fragments (idx 1).\",\n      \"PfSUB1 matures MSP1 in the parasitophorous vacuole just before egress; inhibition blocks processing and reduces invasion (idx 11).\",\n      \"PfSUB2 sheds the ectodomain during invasion, retaining only MSP1(19) on the merozoite (idx 10).\",\n      \"MSP1(19) is a two-EGF-domain module with a U-shaped disulfide-stabilized fold; disulfide bonds required for correct conformation and protective immunogenicity (idx 5, 2, 20, 21).\",\n      \"SUB1-processed MSP1 gains spectrin-binding activity that facilitates erythrocyte rupture during egress (idx 14).\",\n      \"N-terminus binds glycophorin A; the GPA-band 3 complex is essential for infection in vivo (idx 15).\",\n      \"After invasion MSP1(19) is internalized and marks food vacuole biogenesis (idx 19).\",\n      \"In P. berghei, MSP1 is also required for liver-stage merozoite formation (idx 12).\",\n      \"Invasion-inhibitory antibody epitopes are conformational and lie primarily in the first EGF domain; anti-p83 antibodies inhibit all MSP1 complex forms (idx 7, 4, 18).\"\n    ]\n  }\n}","audit_flag":null,"strains":[{"strain":"Pf3D7","gene_id":"PF3D7_0930300","name":null,"product":"merozoite surface protein 1","uniprot_acc":null,"chromosome":null,"start_pos":null},{"strain":"PbANKA","gene_id":"PBANKA_0831000","name":null,"product":"merozoite surface protein 1","uniprot_acc":null,"chromosome":null,"start_pos":null},{"strain":"PkH","gene_id":"PKNH_0728900","name":null,"product":"merozoite surface protein 1","uniprot_acc":null,"chromosome":null,"start_pos":null}],"gene_symbol":"MSP1","evaluation":null}