{"gene":"PF3D7_0501600","run_date":"2026-09-07T10:55:52","timeline":{"discoveries":[{"year":2000,"finding":"RAP1 is required for targeting of RAP2 (PF3D7_0501600) to the rhoptries in P. falciparum. Disruption of RAP1 by gene-targeting produced truncated RAP1 that failed to complex with RAP2 (by immunoprecipitation), and RAP2 was consequently mislocalized to a compartment resembling the endoplasmic reticulum lumen rather than the rhoptries.","method":"Gene disruption (gene targeting), immunoprecipitation, immunofluorescence/subcellular fractionation","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP plus direct localization experiment with functional consequence, clean KO with defined phenotypic readout, peer-reviewed","pmids":["10835342"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2000,"finding":"RAP2 (PF3D7_0501600), together with RAP1 and RAP3, forms the low-molecular-weight rhoptry protein complex in P. falciparum. Truncated RAP1 parasites show that complex formation is required for RAP2 rhoptry targeting, and disruption of RAP1 (which eliminates the complex) does not abolish erythrocyte invasion, indicating the complex is not essential for efficient invasion.","method":"Gene disruption, immunoprecipitation, immunofluorescence","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 2 / Strong — complex membership confirmed by Co-IP alongside clean KO and invasion assay readout, peer-reviewed","pmids":["10835342"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2018,"finding":"RAP2 (PF3D7_0501600) interacts directly with host erythrocyte surface protein CD147, and this interaction is essential for erythrocyte invasion by P. falciparum. The interaction functions at the parasitophorous vacuole formation stage of invasion and is independent of all previously identified invasion-related interactions. Blockade of CD147 with a humanized antibody completely abolished parasite invasion in vitro and in a humanized mouse model.","method":"Binding assays (RAP2–CD147 interaction), antibody blockade (humanized anti-CD147 HP6H8), in vitro invasion inhibition, humanized mouse model","journal":"Blood","confidence":"High","confidence_rationale":"Tier 2 / Strong — direct interaction demonstrated with functional consequence, in vitro and in vivo validation, peer-reviewed","pmids":["29352039"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2007,"finding":"RAP2 (PF3D7_0501600), as part of the low-molecular-mass rhoptry complex, binds to the surface of normal (uninfected) erythrocytes. Using RAP1 and RAP3 gene-disruption mutant parasites and surface iodination experiments, RAP2 (but not RAP3) was identified as responsible for tagging erythrocytes; RAP1-disrupted parasites lost this tagging capacity, suggesting RAP2 is the functional tagging component dependent on RAP1 for surface presentation.","method":"Gene disruption mutants (RAP1- and RAP3-knockout), surface iodination, erythrocyte binding assay","journal":"The Journal of infectious diseases","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean KO parasites with specific assay readout, single lab","pmids":["17624849"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2004,"finding":"Synthetic peptides derived from RAP2 (PF3D7_0501600) bind to red blood cell (RBC) surfaces with high affinity (Kd ~500–950 nM) via specific RBC receptor molecules of 42, 62, and 77 kDa, and these peptides inhibit P. falciparum merozoite invasion in vitro by 54–94% at 200 µM, indicating that RAP2 participates in host-cell recognition during invasion.","method":"Synthetic peptide RBC binding assays, competition binding, SDS-PAGE receptor identification, in vitro invasion inhibition assay","journal":"Biochimie","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — peptide-based binding and invasion inhibition with multiple peptides and receptor identification, single lab","pmids":["14987794"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2009,"finding":"RAP2 (PF3D7_0501600; also referred to as RSP-2) is discharged from rhoptries onto the surface of non-parasitized erythrocytes following merozoite release (abortive/failed invasion), and antibodies to RAP2 on the surface of these tagged erythrocytes mediate their destruction via complement activation and phagocytosis by monocytes, implicating RAP2 in the mechanism of malarial anemia.","method":"Immunofluorescence with anti-rhoptry antibodies on non-infected erythrocytes from in vitro cultures, complement lysis assay, monocyte phagocytosis assay","journal":"Acta tropica","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — multiple functional readouts (complement, phagocytosis) with defined mechanism, single lab","pmids":["19695213"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2002,"finding":"RAP2 (PF3D7_0501600) can functionally compensate for the loss of the related protein RAP3 in P. falciparum, as RAP3-disrupted parasites remain competent for merozoite invasion. RAP3 shares homology with RAP2 and their genes are encoded head-to-tail on chromosome 5, and a phylogenetic analysis indicates the RAP2/RAP3 duplication occurred after divergence of Plasmodium species.","method":"Gene disruption (RAP3 knockout), invasion assay, phylogenetic analysis, genomic analysis","journal":"Infection and immunity","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean KO with invasion phenotype readout, functional complementation inference, single lab","pmids":["12183575"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":1998,"finding":"RAP2 (PF3D7_0501600) protein (p39 product) forms a complex with RAP1 processing products (Pr86/p82/p67) and RAP3 (p37) in the rhoptries. When Pr86 processing was blocked with brefeldin A, fractions containing complexed Pr86 also co-fractionated with p39 (RAP2) and p37 (RAP3), suggesting complex formation occurs prior to or concurrent with rhoptry transport.","method":"Radiolabeling with brefeldin A treatment, size fractionation, immunoblot, immunofluorescence localization","journal":"Molecular and biochemical parasitology","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — co-fractionation under brefeldin A block, multiple readouts, single lab","pmids":["9574915"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2009,"finding":"In P. berghei, a GFP-tagged RAP2/3 protein localizes correctly to the merozoite rhoptries and also shows a distinct apical fluorescence pattern in sporozoites, indicating rhoptry localization in sporozoites as well, and demonstrating that this protein is expressed across multiple invasive stages.","method":"Epitope-tagging (GFP fusion), live fluorescence imaging/immunofluorescence across life-cycle stages","journal":"Molecular and biochemical parasitology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct localization by tagged protein in multiple life stages, single lab","pmids":["19428669"],"is_preprint":false,"attribution":[{"species":"Plasmodium berghei","strain":""}]},{"year":2014,"finding":"In P. yoelii, a fluorescently tagged RAP2/3 protein is secreted into the parasitophorous vacuole (PV) during sporozoite invasion of hepatocytes (as opposed to RON2/RON4 which are lost upon rhoptry discharge). Rhoptry discharge of RAP2/3 occurs only in the presence of the host membrane protein CD81, providing evidence that CD81 is required for productive sporozoite invasion and rhoptry secretion.","method":"Transgenic parasite expressing fluorescent RAP2/3, live imaging during invasion, CD81-deficient host cells","journal":"Cellular microbiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct imaging of tagged protein secretion into PV with CD81-deficient host cell comparison, single lab","pmids":["24798694"],"is_preprint":false,"attribution":[{"species":"Plasmodium yoelii","strain":""}]},{"year":2018,"finding":"In P. berghei, deletion of the rap2/3 gene results in low parasitemia and spontaneous recovery from infection in mice, and complementation of RAP2/3 expression in an attenuated strain (Pb XAT, which has a natural deletion of rap2/3) partially restores virulence, indicating RAP2/3 contributes to parasite virulence.","method":"Gene disruption (RAP2/3-deficient P. berghei), complementation experiment, mouse infection outcome assay","journal":"Experimental parasitology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean KO with complementation rescue, in vivo phenotype, single lab","pmids":["29307564"],"is_preprint":false,"attribution":[{"species":"Plasmodium berghei","strain":"ANKA"}]},{"year":1996,"finding":"RAP2 (PF3D7_0501600) contains two disulfide bridges: Cys24–Cys88 and Cys277–Cys376, as determined by analysis of disulfide bonds in native RAP2. The disulfide bond Cys24–Cys88 is adjacent to a B-cell epitope (E25TEFSKLY32) that is buried/inaccessible in the native, oxidized form but exposed under reducing/denaturing conditions.","method":"Disulfide bond analysis of native protein, immunization and antibody epitope mapping with synthetic peptides","journal":"Molecular and biochemical parasitology","confidence":"Medium","confidence_rationale":"Tier 1-2 / Moderate — biochemical determination of disulfide bond structure with epitope mapping, single lab","pmids":["8946383"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2020,"finding":"RAP2 (PF3D7_0501600) is a component of a PfClag9-associated rhoptry complex that also includes RAP1, RAP3, RhopH2, and RhopH3, as identified by immunoprecipitation of merozoite extracts with anti-PfClag9 antibody followed by mass spectrometry.","method":"Immunoprecipitation of merozoite lysate with anti-PfClag9, mass spectrometry identification","journal":"Infection and immunity","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single Co-IP/MS identification, no reciprocal confirmation specific to RAP2, single lab","pmids":["31712270"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2021,"finding":"RAP2 (PF3D7_0501600) was identified as a member of the low-molecular-mass rhoptry protein complex (together with RAP1) by immuno-affinity purification from P. falciparum schizont-rich parasites followed by LC-MS/MS, confirming complex membership by an independent proteomic approach.","method":"Monoclonal antibody generation, immunoaffinity purification, LC-MS/MS","journal":"Frontiers in cellular and infection microbiology","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single immunoprecipitation/MS confirmation of known complex membership, no new mechanistic detail added, single lab","pmids":["33537242"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]}],"current_model":"PF3D7_0501600 (RAP2) is a rhoptry-resident protein that depends on RAP1 for its correct trafficking to the rhoptries (RAP1 KO mislocalizes RAP2 to the ER and disrupts complex formation); it forms the low-molecular-weight rhoptry complex with RAP1 and RAP3, is secreted into the parasitophorous vacuole during host-cell invasion, binds to uninfected erythrocytes via specific peptide–receptor interactions and via a direct interaction with host CD147 that is essential for invasion, and contributes to parasite virulence in rodent malaria models."},"narrative":{"mechanistic_narrative":"PF3D7_0501600 (RAP2) is a rhoptry-resident protein of Plasmodium falciparum that participates in erythrocyte recognition and invasion by the merozoite [PMID:29352039, PMID:17624849]. It assembles with RAP1 and RAP3 into the low-molecular-weight rhoptry protein complex, forming as early as or concurrent with rhoptry transport, and its correct targeting to the rhoptries is strictly dependent on RAP1: disruption of RAP1 abolishes the complex and mislocalizes RAP2 to an ER-like compartment, yet does not block efficient invasion, indicating the complex per se is not essential for invasion [PMID:10835342, PMID:9574915]. During invasion RAP2 engages the host cell surface—synthetic RAP2 peptides bind erythrocyte receptors of 42, 62, and 77 kDa and inhibit invasion [PMID:14987794], and RAP2 tags uninfected erythrocytes in a RAP1-dependent manner [PMID:17624849]. RAP2 interacts directly with the host erythrocyte protein CD147 at the parasitophorous-vacuole-formation stage, an interaction essential for invasion whose blockade abolishes parasitism in vitro and in a humanized mouse model [PMID:29352039]. Beyond invasion, RAP2 discharged onto non-parasitized erythrocytes during abortive invasion marks those cells for complement- and monocyte-mediated destruction, implicating it in malarial anemia [PMID:19695213]. In rodent malaria, the RAP2/3 ortholog localizes to rhoptries across invasive stages, is secreted into the parasitophorous vacuole during hepatocyte invasion in a host-CD81-dependent manner in P. yoelii [PMID:19428669, PMID:24798694], and contributes to virulence in P. berghei, where rap2/3 deletion attenuates infection and complementation partially restores virulence [PMID:29307564]. RAP2 carries two defined disulfide bridges (Cys24–Cys88, Cys277–Cys376) that shape epitope accessibility [PMID:8946383].","teleology":[{"year":1996,"claim":"Defining the native disulfide architecture of RAP2 established its folded conformation and showed that a B-cell epitope is conformationally buried, framing how the native protein is presented to the immune system.","evidence":"Disulfide bond analysis of native protein with antibody epitope mapping using synthetic peptides","pmids":["8946383"],"confidence":"Medium","gaps":["No full structural model of RAP2","Functional consequence of the disulfide bonds for invasion untested"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":1998,"claim":"Showing that RAP2 (p39) co-fractionates with RAP1 processing products and RAP3 (p37), and that this persists under brefeldin A block, established that the low-molecular-weight rhoptry complex assembles at or before rhoptry transport.","evidence":"Radiolabeling with brefeldin A treatment, size fractionation, and immunoblotting in P. falciparum","pmids":["9574915"],"confidence":"Medium","gaps":["Stoichiometry of the complex not defined","Direct binding interfaces between RAP2 and partners not mapped"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2000,"claim":"Whether RAP2 rhoptry targeting is autonomous or partner-dependent was resolved by RAP1 disruption, which mislocalized RAP2 to an ER-like compartment and abolished complex formation—establishing RAP1 as the trafficking chaperone and showing the complex is dispensable for efficient invasion.","evidence":"RAP1 gene disruption with immunoprecipitation and immunofluorescence/fractionation plus invasion assay in P. falciparum","pmids":["10835342"],"confidence":"High","gaps":["Molecular determinants on RAP2 required for RAP1-dependent trafficking unknown","Why complex is dispensable for invasion despite RAP2 invasion roles not reconciled"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2002,"claim":"The functional relationship between RAP2 and its paralog RAP3 was addressed by RAP3 disruption, which left invasion intact, indicating RAP2 can compensate and that the RAP2/RAP3 duplication postdates Plasmodium species divergence.","evidence":"RAP3 gene disruption with invasion assay, phylogenetic and genomic analysis in P. falciparum","pmids":["12183575"],"confidence":"Medium","gaps":["Direct test of RAP2 loss (rather than inference) not performed","Non-redundant functions of RAP2 vs RAP3 not delineated"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2004,"claim":"The question of whether RAP2 itself contacts the host cell was addressed by synthetic peptide binding, identifying candidate erythrocyte receptors (42, 62, 77 kDa) and showing peptide-mediated invasion inhibition—placing RAP2 in host-cell recognition.","evidence":"Synthetic peptide RBC binding, competition binding, SDS-PAGE receptor identification and invasion inhibition in P. falciparum","pmids":["14987794"],"confidence":"Medium","gaps":["Molecular identity of the 42/62/77 kDa receptors not determined","Peptide binding not validated against native full-length RAP2"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2007,"claim":"Which complex member actually tags erythrocytes was resolved using RAP1- and RAP3-knockout parasites and surface iodination, identifying RAP2 (not RAP3) as the tagging component and confirming its RAP1-dependent surface presentation.","evidence":"RAP1- and RAP3-knockout parasites, surface iodination, and erythrocyte binding assay in P. falciparum","pmids":["17624849"],"confidence":"Medium","gaps":["Receptor engaged during tagging not identified in this study","Single-lab result"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2009,"claim":"The consequence of RAP2 deposition on bystander erythrocytes was addressed by showing discharged RAP2 marks non-parasitized cells for complement- and monocyte-mediated clearance, linking RAP2 to malarial anemia.","evidence":"Immunofluorescence on non-infected erythrocytes plus complement lysis and monocyte phagocytosis assays in P. falciparum","pmids":["19695213"],"confidence":"Medium","gaps":["In vivo contribution to anemia not quantified","Mechanism of RAP2 retention on erythrocyte surface unclear"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2009,"claim":"Whether the RAP2/3 protein functions beyond blood-stage merozoites was addressed in P. berghei, where GFP-tagged RAP2/3 localized to rhoptries in both merozoites and sporozoites, showing expression across invasive stages.","evidence":"GFP-fusion tagging and live/immunofluorescence imaging across life-cycle stages in P. berghei","pmids":["19428669"],"confidence":"Medium","gaps":["Functional role in sporozoites not tested here","Ortholog is fused RAP2/3, not separable RAP2"],"attribution":[{"species":"Plasmodium berghei","strain":""}]},{"year":2014,"claim":"The behavior of RAP2/3 during productive invasion and its host-factor dependence was defined in P. yoelii, where the tagged protein is secreted into the parasitophorous vacuole during hepatocyte invasion in a CD81-dependent manner.","evidence":"Transgenic fluorescent RAP2/3 with live imaging during invasion of CD81-deficient host cells in P. yoelii","pmids":["24798694"],"confidence":"Medium","gaps":["Direct RAP2/3–CD81 interaction not shown","Whether P. falciparum RAP2 behaves identically in hepatocyte invasion untested"],"attribution":[{"species":"Plasmodium yoelii","strain":""}]},{"year":2018,"claim":"The direct host receptor for P. falciparum RAP2 was identified as CD147, an interaction essential for invasion at the parasitophorous-vacuole-formation stage and independent of prior invasion interactions, with antibody blockade abolishing invasion in vitro and in humanized mice.","evidence":"RAP2–CD147 binding assays, humanized anti-CD147 antibody blockade, in vitro invasion inhibition, and humanized mouse model in P. falciparum","pmids":["29352039"],"confidence":"High","gaps":["Structural basis of the RAP2–CD147 interaction not resolved","Relationship of CD147 to the earlier 42/62/77 kDa receptors unclear"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2018,"claim":"The in vivo importance of RAP2/3 for pathogenesis was tested in P. berghei, where rap2/3 deletion attenuated infection and complementation of an attenuated natural-deletion strain partially restored virulence, establishing a virulence contribution.","evidence":"RAP2/3-deficient P. berghei, complementation of Pb XAT strain, and mouse infection outcome assays","pmids":["29307564"],"confidence":"Medium","gaps":["Molecular mechanism linking RAP2/3 to virulence not defined","Fused RAP2/3 ortholog precludes assigning phenotype to RAP2 alone"],"attribution":[{"species":"Plasmodium berghei","strain":"ANKA"}]},{"year":2020,"claim":"Broader complex associations of RAP2 were probed by anti-PfClag9 pulldown, placing RAP2 in a PfClag9-associated rhoptry complex also containing RAP1, RAP3, RhopH2, and RhopH3.","evidence":"Anti-PfClag9 immunoprecipitation of merozoite lysate with mass spectrometry in P. falciparum","pmids":["31712270"],"confidence":"Low","gaps":["Single Co-IP/MS without reciprocal validation specific to RAP2","Direct RAP2–PfClag9 contact not demonstrated"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2021,"claim":"Complex membership was reconfirmed by an independent proteomic approach, identifying RAP2 with RAP1 in the low-molecular-mass rhoptry complex.","evidence":"Monoclonal antibody immunoaffinity purification and LC-MS/MS from schizont-rich P. falciparum","pmids":["33537242"],"confidence":"Low","gaps":["No new mechanistic detail beyond confirming known membership","Single-lab confirmation"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":null,"claim":"How RAP2 engages CD147 at the structural level, whether the previously described erythrocyte receptors correspond to CD147, and the direct role of RAP2 in vacuole formation across species remain unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structure of RAP2 or the RAP2–CD147 interface","Mechanistic link between rhoptry complex assembly and RAP2 host-receptor function unclear","Separable P. falciparum RAP2 loss-of-function not directly tested in vivo"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]}],"mechanism_profile":{"molecular_activity":[],"localization":[],"pathway":[],"complexes":["Low-molecular-weight rhoptry protein complex (RAP1–RAP2–RAP3)","PfClag9-associated rhoptry complex (RAP1, RAP2, RAP3, RhopH2, RhopH3)"],"partners":["RAP1 (TRAFFICKING-DEPENDENT PARTNER)","RAP3","HOST CD147 (ERYTHROCYTE)","HOST CD81 (HEPATOCYTE, P. YOELII)","PFCLAG9","RHOPH2","RHOPH3"],"other_free_text":["Rhoptry targeting of RAP2 strictly depends on RAP1; RAP1 loss mislocalizes RAP2 to an ER-like compartment [#0].","Contains two disulfide bridges Cys24–Cys88 and Cys277–Cys376; Cys24–Cys88 shields a conformational B-cell epitope [#11].","Secreted from rhoptries into the parasitophorous vacuole during invasion [#9].","Discharge onto uninfected erythrocytes marks them for complement- and monocyte-mediated clearance, linking RAP2 to malarial anemia [#5].","In rodent malaria the ortholog is a fused RAP2/3 protein; virulence phenotypes derive from rap2/3 deletion/complementation in P. berghei [#10]."]}},"prefetch_data":{},"corpus_meta":[{"pmid":"10835342","id":"PMC_10835342","title":"RAP1 controls rhoptry targeting of RAP2 in the malaria parasite Plasmodium falciparum.","date":"2000","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/10835342","citation_count":104,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["RAP2"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"1542308","id":"PMC_1542308","title":"The 42-kilodalton rhoptry-associated protein of Plasmodium falciparum.","date":"1992","source":"Molecular and biochemical parasitology","url":"https://pubmed.ncbi.nlm.nih.gov/1542308","citation_count":60,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["curated_ref"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"1279419","id":"PMC_1279419","title":"Inhibitory monoclonal antibodies recognise epitopes adjacent to a proteolytic cleavage site on the RAP-1 protein of Plasmodium falciparum.","date":"1992","source":"Molecular and biochemical parasitology","url":"https://pubmed.ncbi.nlm.nih.gov/1279419","citation_count":55,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["RAP2"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"20823210","id":"PMC_20823210","title":"Multiple antigen peptide vaccines against Plasmodium falciparum malaria.","date":"2010","source":"Infection and immunity","url":"https://pubmed.ncbi.nlm.nih.gov/20823210","citation_count":52,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["PfRAP2"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"29352039","id":"PMC_29352039","title":"Disrupting CD147-RAP2 interaction abrogates erythrocyte invasion by Plasmodium falciparum.","date":"2018","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/29352039","citation_count":42,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["RAP2"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"11220762","id":"PMC_11220762","title":"Efficacy of vaccines containing rhoptry-associated proteins RAP1 and RAP2 of Plasmodium falciparum in Saimiri boliviensis monkeys.","date":"2000","source":"The American journal of tropical medicine and hygiene","url":"https://pubmed.ncbi.nlm.nih.gov/11220762","citation_count":34,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["RAP2"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"12183575","id":"PMC_12183575","title":"Identification and disruption of the gene encoding the third member of the low-molecular-mass rhoptry complex in Plasmodium falciparum.","date":"2002","source":"Infection and immunity","url":"https://pubmed.ncbi.nlm.nih.gov/12183575","citation_count":34,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["RAP2"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"9574915","id":"PMC_9574915","title":"Analysis of the processing of Plasmodium falciparum rhoptry-associated protein 1 and localization of Pr86 to schizont rhoptries and p67 to free merozoites.","date":"1998","source":"Molecular and biochemical parasitology","url":"https://pubmed.ncbi.nlm.nih.gov/9574915","citation_count":34,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["RAP2"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"9169771","id":"PMC_9169771","title":"Assessment of the humoral immune response against Plasmodium falciparum rhoptry-associated proteins 1 and 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parasitology","url":"https://pubmed.ncbi.nlm.nih.gov/19428669","citation_count":32,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["RAP2"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"21175202","id":"PMC_21175202","title":"Proteome analysis reveals a large merozoite surface protein-1 associated complex on the Plasmodium falciparum merozoite surface.","date":"2010","source":"Journal of proteome research","url":"https://pubmed.ncbi.nlm.nih.gov/21175202","citation_count":31,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["PfRAP2"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"17624849","id":"PMC_17624849","title":"Members of the low-molecular-mass rhoptry protein complex of Plasmodium falciparum bind to the surface of normal erythrocytes.","date":"2007","source":"The Journal of infectious 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and T cell recognition of rhoptry-associated protein-1 (RAP-1) and RAP-2 recombinant proteins and peptides of Plasmodium falciparum in migrants and residents of the state of Rondonia, Brazil.","date":"1998","source":"The American journal of tropical medicine and hygiene","url":"https://pubmed.ncbi.nlm.nih.gov/9715934","citation_count":12,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["RAP2"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"29307564","id":"PMC_29307564","title":"Comparative genomics and proteomic analyses between lethal and nonlethal strains of Plasmodium berghei.","date":"2018","source":"Experimental 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2"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":19273,"output_tokens":3882,"usd":0.058024,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":9949,"output_tokens":5461,"usd":0.093135,"stage2_stop_reason":"end_turn"},"total_usd":0.151159,"stage1_batch_id":"msgbatch_01DbiymDmubkPpYvdbAu5a7V","stage2_batch_id":"msgbatch_012TbrWvMRH129T7PQ4SmvrJ","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2000,\n      \"finding\": \"RAP1 is required for targeting of RAP2 (PF3D7_0501600) to the rhoptries in P. falciparum. Disruption of RAP1 by gene-targeting produced truncated RAP1 that failed to complex with RAP2 (by immunoprecipitation), and RAP2 was consequently mislocalized to a compartment resembling the endoplasmic reticulum lumen rather than the rhoptries.\",\n      \"method\": \"Gene disruption (gene targeting), immunoprecipitation, immunofluorescence/subcellular fractionation\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP plus direct localization experiment with functional consequence, clean KO with defined phenotypic readout, peer-reviewed\",\n      \"pmids\": [\"10835342\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"RAP2 (PF3D7_0501600), together with RAP1 and RAP3, forms the low-molecular-weight rhoptry protein complex in P. falciparum. Truncated RAP1 parasites show that complex formation is required for RAP2 rhoptry targeting, and disruption of RAP1 (which eliminates the complex) does not abolish erythrocyte invasion, indicating the complex is not essential for efficient invasion.\",\n      \"method\": \"Gene disruption, immunoprecipitation, immunofluorescence\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — complex membership confirmed by Co-IP alongside clean KO and invasion assay readout, peer-reviewed\",\n      \"pmids\": [\"10835342\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"RAP2 (PF3D7_0501600) interacts directly with host erythrocyte surface protein CD147, and this interaction is essential for erythrocyte invasion by P. falciparum. The interaction functions at the parasitophorous vacuole formation stage of invasion and is independent of all previously identified invasion-related interactions. Blockade of CD147 with a humanized antibody completely abolished parasite invasion in vitro and in a humanized mouse model.\",\n      \"method\": \"Binding assays (RAP2–CD147 interaction), antibody blockade (humanized anti-CD147 HP6H8), in vitro invasion inhibition, humanized mouse model\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — direct interaction demonstrated with functional consequence, in vitro and in vivo validation, peer-reviewed\",\n      \"pmids\": [\"29352039\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"RAP2 (PF3D7_0501600), as part of the low-molecular-mass rhoptry complex, binds to the surface of normal (uninfected) erythrocytes. Using RAP1 and RAP3 gene-disruption mutant parasites and surface iodination experiments, RAP2 (but not RAP3) was identified as responsible for tagging erythrocytes; RAP1-disrupted parasites lost this tagging capacity, suggesting RAP2 is the functional tagging component dependent on RAP1 for surface presentation.\",\n      \"method\": \"Gene disruption mutants (RAP1- and RAP3-knockout), surface iodination, erythrocyte binding assay\",\n      \"journal\": \"The Journal of infectious diseases\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean KO parasites with specific assay readout, single lab\",\n      \"pmids\": [\"17624849\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Synthetic peptides derived from RAP2 (PF3D7_0501600) bind to red blood cell (RBC) surfaces with high affinity (Kd ~500–950 nM) via specific RBC receptor molecules of 42, 62, and 77 kDa, and these peptides inhibit P. falciparum merozoite invasion in vitro by 54–94% at 200 µM, indicating that RAP2 participates in host-cell recognition during invasion.\",\n      \"method\": \"Synthetic peptide RBC binding assays, competition binding, SDS-PAGE receptor identification, in vitro invasion inhibition assay\",\n      \"journal\": \"Biochimie\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — peptide-based binding and invasion inhibition with multiple peptides and receptor identification, single lab\",\n      \"pmids\": [\"14987794\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"RAP2 (PF3D7_0501600; also referred to as RSP-2) is discharged from rhoptries onto the surface of non-parasitized erythrocytes following merozoite release (abortive/failed invasion), and antibodies to RAP2 on the surface of these tagged erythrocytes mediate their destruction via complement activation and phagocytosis by monocytes, implicating RAP2 in the mechanism of malarial anemia.\",\n      \"method\": \"Immunofluorescence with anti-rhoptry antibodies on non-infected erythrocytes from in vitro cultures, complement lysis assay, monocyte phagocytosis assay\",\n      \"journal\": \"Acta tropica\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — multiple functional readouts (complement, phagocytosis) with defined mechanism, single lab\",\n      \"pmids\": [\"19695213\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"RAP2 (PF3D7_0501600) can functionally compensate for the loss of the related protein RAP3 in P. falciparum, as RAP3-disrupted parasites remain competent for merozoite invasion. RAP3 shares homology with RAP2 and their genes are encoded head-to-tail on chromosome 5, and a phylogenetic analysis indicates the RAP2/RAP3 duplication occurred after divergence of Plasmodium species.\",\n      \"method\": \"Gene disruption (RAP3 knockout), invasion assay, phylogenetic analysis, genomic analysis\",\n      \"journal\": \"Infection and immunity\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean KO with invasion phenotype readout, functional complementation inference, single lab\",\n      \"pmids\": [\"12183575\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"RAP2 (PF3D7_0501600) protein (p39 product) forms a complex with RAP1 processing products (Pr86/p82/p67) and RAP3 (p37) in the rhoptries. When Pr86 processing was blocked with brefeldin A, fractions containing complexed Pr86 also co-fractionated with p39 (RAP2) and p37 (RAP3), suggesting complex formation occurs prior to or concurrent with rhoptry transport.\",\n      \"method\": \"Radiolabeling with brefeldin A treatment, size fractionation, immunoblot, immunofluorescence localization\",\n      \"journal\": \"Molecular and biochemical parasitology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — co-fractionation under brefeldin A block, multiple readouts, single lab\",\n      \"pmids\": [\"9574915\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"In P. berghei, a GFP-tagged RAP2/3 protein localizes correctly to the merozoite rhoptries and also shows a distinct apical fluorescence pattern in sporozoites, indicating rhoptry localization in sporozoites as well, and demonstrating that this protein is expressed across multiple invasive stages.\",\n      \"method\": \"Epitope-tagging (GFP fusion), live fluorescence imaging/immunofluorescence across life-cycle stages\",\n      \"journal\": \"Molecular and biochemical parasitology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct localization by tagged protein in multiple life stages, single lab\",\n      \"pmids\": [\"19428669\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium berghei\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"In P. yoelii, a fluorescently tagged RAP2/3 protein is secreted into the parasitophorous vacuole (PV) during sporozoite invasion of hepatocytes (as opposed to RON2/RON4 which are lost upon rhoptry discharge). Rhoptry discharge of RAP2/3 occurs only in the presence of the host membrane protein CD81, providing evidence that CD81 is required for productive sporozoite invasion and rhoptry secretion.\",\n      \"method\": \"Transgenic parasite expressing fluorescent RAP2/3, live imaging during invasion, CD81-deficient host cells\",\n      \"journal\": \"Cellular microbiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct imaging of tagged protein secretion into PV with CD81-deficient host cell comparison, single lab\",\n      \"pmids\": [\"24798694\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium yoelii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"In P. berghei, deletion of the rap2/3 gene results in low parasitemia and spontaneous recovery from infection in mice, and complementation of RAP2/3 expression in an attenuated strain (Pb XAT, which has a natural deletion of rap2/3) partially restores virulence, indicating RAP2/3 contributes to parasite virulence.\",\n      \"method\": \"Gene disruption (RAP2/3-deficient P. berghei), complementation experiment, mouse infection outcome assay\",\n      \"journal\": \"Experimental parasitology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean KO with complementation rescue, in vivo phenotype, single lab\",\n      \"pmids\": [\"29307564\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium berghei\", \"strain\": \"ANKA\"}]\n    },\n    {\n      \"year\": 1996,\n      \"finding\": \"RAP2 (PF3D7_0501600) contains two disulfide bridges: Cys24–Cys88 and Cys277–Cys376, as determined by analysis of disulfide bonds in native RAP2. The disulfide bond Cys24–Cys88 is adjacent to a B-cell epitope (E25TEFSKLY32) that is buried/inaccessible in the native, oxidized form but exposed under reducing/denaturing conditions.\",\n      \"method\": \"Disulfide bond analysis of native protein, immunization and antibody epitope mapping with synthetic peptides\",\n      \"journal\": \"Molecular and biochemical parasitology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — biochemical determination of disulfide bond structure with epitope mapping, single lab\",\n      \"pmids\": [\"8946383\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"RAP2 (PF3D7_0501600) is a component of a PfClag9-associated rhoptry complex that also includes RAP1, RAP3, RhopH2, and RhopH3, as identified by immunoprecipitation of merozoite extracts with anti-PfClag9 antibody followed by mass spectrometry.\",\n      \"method\": \"Immunoprecipitation of merozoite lysate with anti-PfClag9, mass spectrometry identification\",\n      \"journal\": \"Infection and immunity\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single Co-IP/MS identification, no reciprocal confirmation specific to RAP2, single lab\",\n      \"pmids\": [\"31712270\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"RAP2 (PF3D7_0501600) was identified as a member of the low-molecular-mass rhoptry protein complex (together with RAP1) by immuno-affinity purification from P. falciparum schizont-rich parasites followed by LC-MS/MS, confirming complex membership by an independent proteomic approach.\",\n      \"method\": \"Monoclonal antibody generation, immunoaffinity purification, LC-MS/MS\",\n      \"journal\": \"Frontiers in cellular and infection microbiology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single immunoprecipitation/MS confirmation of known complex membership, no new mechanistic detail added, single lab\",\n      \"pmids\": [\"33537242\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    }\n  ],\n  \"current_model\": \"PF3D7_0501600 (RAP2) is a rhoptry-resident protein that depends on RAP1 for its correct trafficking to the rhoptries (RAP1 KO mislocalizes RAP2 to the ER and disrupts complex formation); it forms the low-molecular-weight rhoptry complex with RAP1 and RAP3, is secreted into the parasitophorous vacuole during host-cell invasion, binds to uninfected erythrocytes via specific peptide–receptor interactions and via a direct interaction with host CD147 that is essential for invasion, and contributes to parasite virulence in rodent malaria models.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"PF3D7_0501600 (RAP2) is a rhoptry-resident protein of Plasmodium falciparum that participates in erythrocyte recognition and invasion by the merozoite [#2, #3]. It assembles with RAP1 and RAP3 into the low-molecular-weight rhoptry protein complex, forming as early as or concurrent with rhoptry transport, and its correct targeting to the rhoptries is strictly dependent on RAP1: disruption of RAP1 abolishes the complex and mislocalizes RAP2 to an ER-like compartment, yet does not block efficient invasion, indicating the complex per se is not essential for invasion [#0, #1, #7]. During invasion RAP2 engages the host cell surface—synthetic RAP2 peptides bind erythrocyte receptors of 42, 62, and 77 kDa and inhibit invasion [#4], and RAP2 tags uninfected erythrocytes in a RAP1-dependent manner [#3]. RAP2 interacts directly with the host erythrocyte protein CD147 at the parasitophorous-vacuole-formation stage, an interaction essential for invasion whose blockade abolishes parasitism in vitro and in a humanized mouse model [#2]. Beyond invasion, RAP2 discharged onto non-parasitized erythrocytes during abortive invasion marks those cells for complement- and monocyte-mediated destruction, implicating it in malarial anemia [#5]. In rodent malaria, the RAP2/3 ortholog localizes to rhoptries across invasive stages, is secreted into the parasitophorous vacuole during hepatocyte invasion in a host-CD81-dependent manner in P. yoelii [#8, #9], and contributes to virulence in P. berghei, where rap2/3 deletion attenuates infection and complementation partially restores virulence [#10]. RAP2 carries two defined disulfide bridges (Cys24–Cys88, Cys277–Cys376) that shape epitope accessibility [#11].\",\n  \"teleology\": [\n    {\n      \"year\": 1996,\n      \"claim\": \"Defining the native disulfide architecture of RAP2 established its folded conformation and showed that a B-cell epitope is conformationally buried, framing how the native protein is presented to the immune system.\",\n      \"evidence\": \"Disulfide bond analysis of native protein with antibody epitope mapping using synthetic peptides\",\n      \"pmids\": [\"8946383\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"No full structural model of RAP2\", \"Functional consequence of the disulfide bonds for invasion untested\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 1998,\n      \"claim\": \"Showing that RAP2 (p39) co-fractionates with RAP1 processing products and RAP3 (p37), and that this persists under brefeldin A block, established that the low-molecular-weight rhoptry complex assembles at or before rhoptry transport.\",\n      \"evidence\": \"Radiolabeling with brefeldin A treatment, size fractionation, and immunoblotting in P. falciparum\",\n      \"pmids\": [\"9574915\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Stoichiometry of the complex not defined\", \"Direct binding interfaces between RAP2 and partners not mapped\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2000,\n      \"claim\": \"Whether RAP2 rhoptry targeting is autonomous or partner-dependent was resolved by RAP1 disruption, which mislocalized RAP2 to an ER-like compartment and abolished complex formation—establishing RAP1 as the trafficking chaperone and showing the complex is dispensable for efficient invasion.\",\n      \"evidence\": \"RAP1 gene disruption with immunoprecipitation and immunofluorescence/fractionation plus invasion assay in P. falciparum\",\n      \"pmids\": [\"10835342\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Molecular determinants on RAP2 required for RAP1-dependent trafficking unknown\", \"Why complex is dispensable for invasion despite RAP2 invasion roles not reconciled\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"The functional relationship between RAP2 and its paralog RAP3 was addressed by RAP3 disruption, which left invasion intact, indicating RAP2 can compensate and that the RAP2/RAP3 duplication postdates Plasmodium species divergence.\",\n      \"evidence\": \"RAP3 gene disruption with invasion assay, phylogenetic and genomic analysis in P. falciparum\",\n      \"pmids\": [\"12183575\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Direct test of RAP2 loss (rather than inference) not performed\", \"Non-redundant functions of RAP2 vs RAP3 not delineated\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"The question of whether RAP2 itself contacts the host cell was addressed by synthetic peptide binding, identifying candidate erythrocyte receptors (42, 62, 77 kDa) and showing peptide-mediated invasion inhibition—placing RAP2 in host-cell recognition.\",\n      \"evidence\": \"Synthetic peptide RBC binding, competition binding, SDS-PAGE receptor identification and invasion inhibition in P. falciparum\",\n      \"pmids\": [\"14987794\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Molecular identity of the 42/62/77 kDa receptors not determined\", \"Peptide binding not validated against native full-length RAP2\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Which complex member actually tags erythrocytes was resolved using RAP1- and RAP3-knockout parasites and surface iodination, identifying RAP2 (not RAP3) as the tagging component and confirming its RAP1-dependent surface presentation.\",\n      \"evidence\": \"RAP1- and RAP3-knockout parasites, surface iodination, and erythrocyte binding assay in P. falciparum\",\n      \"pmids\": [\"17624849\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Receptor engaged during tagging not identified in this study\", \"Single-lab result\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"The consequence of RAP2 deposition on bystander erythrocytes was addressed by showing discharged RAP2 marks non-parasitized cells for complement- and monocyte-mediated clearance, linking RAP2 to malarial anemia.\",\n      \"evidence\": \"Immunofluorescence on non-infected erythrocytes plus complement lysis and monocyte phagocytosis assays in P. falciparum\",\n      \"pmids\": [\"19695213\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"In vivo contribution to anemia not quantified\", \"Mechanism of RAP2 retention on erythrocyte surface unclear\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Whether the RAP2/3 protein functions beyond blood-stage merozoites was addressed in P. berghei, where GFP-tagged RAP2/3 localized to rhoptries in both merozoites and sporozoites, showing expression across invasive stages.\",\n      \"evidence\": \"GFP-fusion tagging and live/immunofluorescence imaging across life-cycle stages in P. berghei\",\n      \"pmids\": [\"19428669\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Functional role in sporozoites not tested here\", \"Ortholog is fused RAP2/3, not separable RAP2\"],\n      \"attribution\": [{\"species\": \"Plasmodium berghei\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"The behavior of RAP2/3 during productive invasion and its host-factor dependence was defined in P. yoelii, where the tagged protein is secreted into the parasitophorous vacuole during hepatocyte invasion in a CD81-dependent manner.\",\n      \"evidence\": \"Transgenic fluorescent RAP2/3 with live imaging during invasion of CD81-deficient host cells in P. yoelii\",\n      \"pmids\": [\"24798694\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Direct RAP2/3–CD81 interaction not shown\", \"Whether P. falciparum RAP2 behaves identically in hepatocyte invasion untested\"],\n      \"attribution\": [{\"species\": \"Plasmodium yoelii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"The direct host receptor for P. falciparum RAP2 was identified as CD147, an interaction essential for invasion at the parasitophorous-vacuole-formation stage and independent of prior invasion interactions, with antibody blockade abolishing invasion in vitro and in humanized mice.\",\n      \"evidence\": \"RAP2–CD147 binding assays, humanized anti-CD147 antibody blockade, in vitro invasion inhibition, and humanized mouse model in P. falciparum\",\n      \"pmids\": [\"29352039\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Structural basis of the RAP2–CD147 interaction not resolved\", \"Relationship of CD147 to the earlier 42/62/77 kDa receptors unclear\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"The in vivo importance of RAP2/3 for pathogenesis was tested in P. berghei, where rap2/3 deletion attenuated infection and complementation of an attenuated natural-deletion strain partially restored virulence, establishing a virulence contribution.\",\n      \"evidence\": \"RAP2/3-deficient P. berghei, complementation of Pb XAT strain, and mouse infection outcome assays\",\n      \"pmids\": [\"29307564\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Molecular mechanism linking RAP2/3 to virulence not defined\", \"Fused RAP2/3 ortholog precludes assigning phenotype to RAP2 alone\"],\n      \"attribution\": [{\"species\": \"Plasmodium berghei\", \"strain\": \"ANKA\"}]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Broader complex associations of RAP2 were probed by anti-PfClag9 pulldown, placing RAP2 in a PfClag9-associated rhoptry complex also containing RAP1, RAP3, RhopH2, and RhopH3.\",\n      \"evidence\": \"Anti-PfClag9 immunoprecipitation of merozoite lysate with mass spectrometry in P. falciparum\",\n      \"pmids\": [\"31712270\"],\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Single Co-IP/MS without reciprocal validation specific to RAP2\", \"Direct RAP2–PfClag9 contact not demonstrated\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Complex membership was reconfirmed by an independent proteomic approach, identifying RAP2 with RAP1 in the low-molecular-mass rhoptry complex.\",\n      \"evidence\": \"Monoclonal antibody immunoaffinity purification and LC-MS/MS from schizont-rich P. falciparum\",\n      \"pmids\": [\"33537242\"],\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"No new mechanistic detail beyond confirming known membership\", \"Single-lab confirmation\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How RAP2 engages CD147 at the structural level, whether the previously described erythrocyte receptors correspond to CD147, and the direct role of RAP2 in vacuole formation across species remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"No structure of RAP2 or the RAP2–CD147 interface\", \"Mechanistic link between rhoptry complex assembly and RAP2 host-receptor function unclear\", \"Separable P. falciparum RAP2 loss-of-function not directly tested in vivo\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0005102\", \"supporting_discovery_ids\": [2, 3, 4]},\n      {\"term_id\": \"GO:0050839\", \"supporting_discovery_ids\": [2]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0020008\", \"supporting_discovery_ids\": [0, 1, 7, 8]},\n      {\"term_id\": \"GO:0020002\", \"supporting_discovery_ids\": [9]},\n      {\"term_id\": \"GO:0009986\", \"supporting_discovery_ids\": [3, 4, 5]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0044409\", \"supporting_discovery_ids\": [2, 4]},\n      {\"term_id\": \"GO:0044406\", \"supporting_discovery_ids\": [2, 4]}\n    ],\n    \"complexes\": [\n      \"Low-molecular-weight rhoptry protein complex (RAP1–RAP2–RAP3)\",\n      \"PfClag9-associated rhoptry complex (RAP1, RAP2, RAP3, RhopH2, RhopH3)\"\n    ],\n    \"partners\": [\n      \"RAP1 (trafficking-dependent partner)\",\n      \"RAP3\",\n      \"host CD147 (erythrocyte)\",\n      \"host CD81 (hepatocyte, P. yoelii)\",\n      \"PfClag9\",\n      \"RhopH2\",\n      \"RhopH3\"\n    ],\n    \"other_free_text\": [\n      \"Rhoptry targeting of RAP2 strictly depends on RAP1; RAP1 loss mislocalizes RAP2 to an ER-like compartment [#0].\",\n      \"Contains two disulfide bridges Cys24–Cys88 and Cys277–Cys376; Cys24–Cys88 shields a conformational B-cell epitope [#11].\",\n      \"Secreted from rhoptries into the parasitophorous vacuole during invasion [#9].\",\n      \"Discharge onto uninfected erythrocytes marks them for complement- and monocyte-mediated clearance, linking RAP2 to malarial anemia [#5].\",\n      \"In rodent malaria the ortholog is a fused RAP2/3 protein; virulence phenotypes derive from rap2/3 deletion/complementation in P. berghei [#10].\"\n    ]\n  }\n}","audit_flag":{"gene":"PF3D7_0501600","tier":"IDENTITY_CHECK","verdict":"identity unverified","subtype":"names_other_cards","uniprot_band":"","rules_fired":"R12","issue":"No cited paper names this card; 12 of 13 cited papers name other catalogue genes (PF3D7_1410400, PF3D7_0501500, PF3D7_1452000). The summary may describe one of those genes."},"strains":[{"strain":"Pf3D7","gene_id":"PF3D7_0501600","name":null,"product":"rhoptry-associated protein 2","uniprot_acc":null,"chromosome":null,"start_pos":null}],"gene_symbol":"RAP2","evaluation":null}