{"gene":"PF3D7_0817700","run_date":"2026-09-08T12:51:27","timeline":{"discoveries":[{"year":2026,"finding":"Cryo-EM structure of the endogenous P. falciparum moving junction complex (purified from invasion-stalled parasites) reveals a 1:1:1:1 assembly of PfAMA1, PfRON2, PfRON4, and PfRON5. PfRON5, together with PfRON2 and PfRON4, forms a large, basic platform inside the red blood cell that electrostatically engages the RBC membrane and wedges seven amphipathic helices deep into the lipid bilayer, indicating an active role in host-membrane remodeling during invasion.","method":"Cryo-EM structural determination of endogenous complex purified from invasion-stalled P. falciparum parasites","journal":"Cell","confidence":"High","confidence_rationale":"Tier 1 / Strong — native complex purified directly from parasites, high-resolution cryo-EM structure with atomic-level mechanistic detail in a single rigorous study","pmids":["42379167"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2010,"finding":"PfRON5 was identified as a ~110 kDa protein expressed in merozoite and schizont stages. Anti-AMA1 antibody co-immunoprecipitates PfRON5 together with PfRON2 and PfRON4, placing PfRON5 as a component of the PfAMA1–RON complex associated with the moving junction during erythrocyte invasion.","method":"Co-immunoprecipitation with anti-AMA1 antibody, Western blot, stage-specific expression analysis","journal":"Gene","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — single Co-IP experiment identifying complex membership, confirmed across multiple papers but original identification from single lab","pmids":["21185360","20228060"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":"FCB-2"}]},{"year":2013,"finding":"Synthetic peptides derived from PfRON5 bind to human erythrocytes in a saturable manner sensitive to chymotrypsin and trypsin treatment of red blood cells, and inhibit P. falciparum merozoite invasion in vitro, demonstrating a direct functional role for PfRON5–erythrocyte interaction in invasion.","method":"Erythrocyte-binding assay with synthetic peptides, invasion inhibition assay","journal":"Peptides","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — direct functional assay (binding + inhibition) but single lab, single study, peptide-based approach","pmids":["23932940"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2015,"finding":"PvRON5 in P. vivax (VCG-1 strain) localizes to the rhoptry neck of late schizonts together with PvRON2 and PvRON4, undergoes proteolytic processing (detected as ~85 and ~30 kDa fragments in parasite lysate), and a recombinant fragment binds human reticulocytes with marked preference over normocytes, suggesting a direct role in host cell targeting.","method":"Immunofluorescence assay, Western blot of parasite lysate, recombinant protein reticulocyte-binding assay, polyclonal antibody detection","journal":"Malaria journal","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods (IFA localization, binding assay, proteolytic processing), single lab","pmids":["25888962"],"is_preprint":false,"attribution":[{"species":"Plasmodium vivax","strain":"VCG-1"}]},{"year":2014,"finding":"P. yoelii RON5 (PyRON5) localizes to the rhoptry neck of late schizont merozoites and to the rhoptry of sporozoites, partitions into water-insoluble membrane fractions without a predicted transmembrane domain, and co-immunoprecipitates with PyRON4, PyRON2, and PyAMA1 in late schizont extracts, indicating that PyRON5 associates with the moving junction complex indirectly via other MJ components.","method":"Indirect immunofluorescence assay, immunoelectron microscopy, co-immunoprecipitation, membrane fractionation, full-length cDNA sequencing","journal":"Parasitology international","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods (IFA, immuno-EM, Co-IP, fractionation) in a single focused study","pmids":["25102354"],"is_preprint":false,"attribution":[{"species":"Plasmodium yoelii","strain":""}]},{"year":2020,"finding":"In P. berghei sporozoites, RON5 forms a complex with RON2 and RON4 (shown by co-immunoprecipitation from oocyst-derived sporozoite extracts). Sporozoite stage-specific gene knockdown of RON5 significantly reduces sporozoite attachment ability and invasion of mosquito salivary glands. Unlike RON2 and RON4 (which reciprocally affect each other's trafficking to rhoptries), RON5 is independently transported to rhoptries in developing sporozoites.","method":"Co-immunoprecipitation from sporozoite extracts, sporozoite stage-specific gene knockdown, invasion and attachment assays","journal":"mSphere","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP demonstrating complex formation, combined with functional gene knockdown showing specific attachment/invasion phenotype and trafficking epistasis, single lab with multiple orthogonal methods","pmids":["32817376"],"is_preprint":false,"attribution":[{"species":"Plasmodium berghei","strain":""}]},{"year":2019,"finding":"In P. berghei sporozoites, RON5 localizes to rhoptries by immunoelectron microscopy, whereas in merozoites it is at the rhoptry neck — demonstrating that the same protein distributes to different subcompartments of the rhoptry in the two invasive stages.","method":"Immuno-electron microscopy, transcriptional analysis of rhoptry genes in sporozoites","journal":"Frontiers in cellular and infection microbiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — immuno-EM localization with functional implication for stage-specific invasion, single lab","pmids":["31552198"],"is_preprint":false,"attribution":[{"species":"Plasmodium berghei","strain":""}]},{"year":2010,"finding":"The R1 inhibitory peptide blocks PfAMA1 interaction with the PfRON complex (which includes PfRON5) by binding the PfAMA1 hydrophobic trough; this interaction occurs after merozoite reorientation and engagement of the actomyosin motor, placing AMA1–RON complex formation (and therefore RON5's participation in the complex) at a step that precedes rhoptry release.","method":"Peptide binding assay (R1 peptide competition), invasion inhibition assay with defined mechanistic staging","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — mechanistic staging by invasion inhibition and peptide competition assays, but RON5 contribution inferred as complex member rather than tested independently","pmids":["20228060"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]}],"current_model":"PfRON5/PF3D7_0817700 is a rhoptry neck protein that forms a stoichiometric 1:1:1:1 complex with PfAMA1, PfRON2, and PfRON4 at the moving junction during erythrocyte invasion; its cryo-EM structure shows that together with RON2 and RON4 it creates a basic, amphipathic platform that electrostatically engages and remodels the host RBC membrane from the cytoplasmic face, while its surface-exposed peptides also directly contact the RBC exterior to facilitate invasion; in sporozoites (P. berghei) it forms the same RON2/RON4/RON5 complex, is independently trafficked to rhoptries, and is required for sporozoite attachment to and invasion of mosquito salivary glands."},"narrative":{"mechanistic_narrative":"RON5 (PF3D7_0817700) is a rhoptry neck protein that functions as a core component of the moving junction complex that Plasmodium parasites assemble at the host-cell interface during invasion [PMID:42379167, PMID:21185360, PMID:20228060]. In P. falciparum, RON5 assembles in a 1:1:1:1 stoichiometric complex with AMA1, RON2, and RON4, and a cryo-EM structure of the endogenous complex shows that RON5, together with RON2 and RON4, forms a large, basic platform on the cytoplasmic (intracellular) face of the red blood cell that electrostatically engages the erythrocyte membrane and wedges amphipathic helices into the lipid bilayer, implicating RON5 in active remodeling of the host membrane during invasion [PMID:42379167]. RON5 was originally identified as a ~110 kDa merozoite/schizont-stage protein that co-immunoprecipitates with AMA1 alongside RON2 and RON4 [PMID:21185360, PMID:20228060], and its incorporation into the AMA1–RON complex occurs after merozoite reorientation and actomyosin-motor engagement, preceding rhoptry release [PMID:20228060]. Beyond its intracellular platform role, RON5-derived peptides bind human erythrocytes in a protease-sensitive, saturable manner and inhibit merozoite invasion, indicating a direct RON5–erythrocyte contact that contributes to invasion [PMID:23932940]. The protein's role extends across invasive stages and species: in P. berghei sporozoites RON5 forms a RON2/RON4/RON5 complex, is trafficked to rhoptries independently of RON2 and RON4, and is required for sporozoite attachment to and invasion of mosquito salivary glands [PMID:32817376], and it relocates between the rhoptry neck (merozoites) and rhoptry body (sporozoites) in a stage-specific manner [PMID:31552198]. Orthologs in P. vivax and P. yoelii show conserved rhoptry-neck localization, proteolytic processing, and host-cell (reticulocyte) binding preference [PMID:25888962, PMID:25102354].","teleology":[{"year":2010,"claim":"Establishing whether RON5 is part of the invasion machinery, this work identified RON5 as a stage-specific merozoite/schizont protein physically associated with the AMA1–RON moving junction complex.","evidence":"Anti-AMA1 co-immunoprecipitation, Western blot, and stage-specific expression analysis in P. falciparum FCB-2","pmids":["21185360","20228060"],"confidence":"Medium","gaps":["Single Co-IP does not define whether RON5 binds AMA1 directly or via other RON subunits","No structural or stoichiometric information","Functional necessity of RON5 not tested"],"attribution":[{"species":"Plasmodium falciparum","strain":"FCB-2"}]},{"year":2010,"claim":"To place complex assembly within the invasion sequence, R1-peptide competition showed AMA1–RON complex formation (and thus RON5's participation) occurs after reorientation and motor engagement but before rhoptry release.","evidence":"R1 inhibitory peptide competition and staged invasion-inhibition assays in P. falciparum","pmids":["20228060"],"confidence":"Medium","gaps":["RON5's contribution was inferred as a complex member, not tested independently","Does not resolve RON5's specific molecular action at the junction"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2013,"claim":"Addressing whether RON5 directly engages the host cell, RON5-derived peptides were shown to bind erythrocytes in a saturable, protease-sensitive manner and block invasion, implicating a direct RON5–erythrocyte contact.","evidence":"Synthetic peptide erythrocyte-binding and invasion-inhibition assays in P. falciparum","pmids":["23932940"],"confidence":"Medium","gaps":["Peptide-based approach may not reflect native full-length protein behavior","Erythrocyte receptor not identified","Not confirmed with recombinant full-length RON5 or genetic depletion"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2014,"claim":"Testing conservation and mode of complex association, PyRON5 was shown to localize to rhoptries, partition into membrane fractions despite lacking a predicted transmembrane domain, and associate with the MJ complex indirectly through other components.","evidence":"IFA, immuno-EM, Co-IP, and membrane fractionation in P. yoelii","pmids":["25102354"],"confidence":"Medium","gaps":["Mechanism of membrane partitioning without a TM domain unresolved","Which subunit directly recruits RON5 not defined","No invasion phenotype from genetic depletion"],"attribution":[{"species":"Plasmodium yoelii","strain":""}]},{"year":2015,"claim":"Extending to P. vivax, PvRON5 was shown to localize to the rhoptry neck with RON2/RON4, undergo proteolytic processing, and preferentially bind reticulocytes, linking RON5 to host-cell tropism.","evidence":"IFA, Western blot, and recombinant reticulocyte-binding assay in P. vivax VCG-1","pmids":["25888962"],"confidence":"Medium","gaps":["Functional consequence of proteolytic processing unknown","Reticulocyte receptor unidentified","Binding preference not linked to invasion outcome genetically"],"attribution":[{"species":"Plasmodium vivax","strain":"VCG-1"}]},{"year":2019,"claim":"To explain stage-specific invasion behavior, immuno-EM revealed that RON5 occupies the rhoptry neck in merozoites but the rhoptry body in sporozoites, showing the same protein redistributes across invasive stages.","evidence":"Immuno-electron microscopy and rhoptry-gene transcriptional analysis in P. berghei","pmids":["31552198"],"confidence":"Medium","gaps":["Functional significance of subcompartment switch unresolved","Trafficking signals directing the switch not defined"],"attribution":[{"species":"Plasmodium berghei","strain":""}]},{"year":2020,"claim":"Providing direct genetic evidence of function, sporozoite-stage knockdown of RON5 impaired attachment to and invasion of mosquito salivary glands, and RON5 was shown to traffic to rhoptries independently of RON2/RON4.","evidence":"Reciprocal Co-IP from sporozoite extracts plus stage-specific knockdown with attachment/invasion assays in P. berghei","pmids":["32817376"],"confidence":"High","gaps":["Molecular basis of the attachment defect not defined","Trafficking signal enabling RON2/RON4-independent transport unknown","Blood-stage genetic requirement for RON5 not tested here"],"attribution":[{"species":"Plasmodium berghei","strain":""}]},{"year":2026,"claim":"To define RON5's molecular action at the junction, cryo-EM of the endogenous P. falciparum complex resolved a 1:1:1:1 AMA1–RON2–RON4–RON5 assembly in which RON5, RON2, and RON4 build a basic platform that electrostatically engages and wedges amphipathic helices into the RBC membrane from the cytoplasmic face.","evidence":"Cryo-EM of endogenous complex purified from invasion-stalled P. falciparum parasites","pmids":["42379167"],"confidence":"High","gaps":["Which specific residues/helices of RON5 (versus RON2/RON4) insert into the membrane not individually dissected","Dynamics of membrane remodeling during active invasion not captured","Relationship between the intracellular platform and the surface-exposed RON5 peptide contacts not fully reconciled"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":null,"claim":"How RON5 crosses the erythrocyte membrane to establish an intracellular basic platform while also presenting surface-exposed peptides, and what specific molecular contribution RON5 makes distinct from RON2/RON4, remains unresolved.","evidence":"","pmids":[],"confidence":"High","gaps":["No host receptor for RON5 identified","RON5-specific contribution to membrane remodeling not isolated from other subunits","Mechanism of RON5 insertion/translocation across the RBC membrane unknown"],"attribution":[]}],"mechanism_profile":{"molecular_activity":[],"localization":[],"pathway":[],"complexes":["Moving junction complex: AMA1–RON2–RON4–RON5 (1:1:1:1 stoichiometry) in P. falciparum merozoites [#0, #1]","RON2–RON4–RON5 complex in P. berghei sporozoites [#5]"],"partners":["PFAMA1 (VIA THE AMA1–RON COMPLEX) [#0, #1, #7]","PFRON2 [#0, #1, #4, #5]","PFRON4 [#0, #1, #4, #5]"],"other_free_text":["Expressed in merozoite and schizont stages as a ~110 kDa protein [#1]","Undergoes proteolytic processing (~85 and ~30 kDa fragments in P. vivax) [#3]","Partitions into water-insoluble membrane fractions despite lacking a predicted transmembrane domain (P. yoelii) [#4]","Trafficked to rhoptries independently of RON2 and RON4 in P. berghei sporozoites [#5]","Redistributes from rhoptry neck (merozoites) to rhoptry body (sporozoites) [#6]","Required for sporozoite attachment to and invasion of mosquito salivary glands (P. berghei) [#5]","Recombinant/synthetic RON5 fragments bind host cells: erythrocytes in P. falciparum [#2] and reticulocytes preferentially in P. vivax [#3]"]}},"prefetch_data":{},"corpus_meta":[{"pmid":"20228060","id":"PMC_20228060","title":"Interaction between Plasmodium falciparum apical membrane antigen 1 and the rhoptry neck protein complex defines a key step in the erythrocyte invasion process of malaria parasites.","date":"2010","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/20228060","citation_count":213,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["RON5"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"18952195","id":"PMC_18952195","title":"Rhoptry neck protein RON2 forms a complex with microneme protein AMA1 in Plasmodium falciparum merozoites.","date":"2008","source":"Parasitology international","url":"https://pubmed.ncbi.nlm.nih.gov/18952195","citation_count":140,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["RON5"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"19165323","id":"PMC_19165323","title":"An inhibitory antibody blocks interactions between components of the malarial invasion machinery.","date":"2009","source":"PLoS pathogens","url":"https://pubmed.ncbi.nlm.nih.gov/19165323","citation_count":140,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["curated_ref"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"21185360","id":"PMC_21185360","title":"Identification of the Plasmodium falciparum rhoptry neck protein 5 (PfRON5).","date":"2010","source":"Gene","url":"https://pubmed.ncbi.nlm.nih.gov/21185360","citation_count":18,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["RON5","PfRON5"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"25888962","id":"PMC_25888962","title":"The Plasmodium vivax rhoptry neck protein 5 is expressed in the apical pole of Plasmodium vivax VCG-1 strain schizonts and binds to human reticulocytes.","date":"2015","source":"Malaria journal","url":"https://pubmed.ncbi.nlm.nih.gov/25888962","citation_count":18,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["RON5","PvRON5"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"31552198","id":"PMC_31552198","title":"Expression and Localization Profiles of Rhoptry Proteins in Plasmodium berghei Sporozoites.","date":"2019","source":"Frontiers in cellular and infection microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/31552198","citation_count":17,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["RON5"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"25102354","id":"PMC_25102354","title":"Expression and localization of rhoptry neck protein 5 in merozoites and sporozoites of Plasmodium yoelii.","date":"2014","source":"Parasitology international","url":"https://pubmed.ncbi.nlm.nih.gov/25102354","citation_count":17,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["RON5","PyRON5"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"32817376","id":"PMC_32817376","title":"Detection of the Rhoptry Neck Protein Complex in Plasmodium Sporozoites and Its Contribution to Sporozoite Invasion of Salivary Glands.","date":"2020","source":"mSphere","url":"https://pubmed.ncbi.nlm.nih.gov/32817376","citation_count":15,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["RON5"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"29488316","id":"PMC_29488316","title":"Receptor-ligand and parasite protein-protein interactions in Plasmodium vivax: Analysing rhoptry neck proteins 2 and 4.","date":"2018","source":"Cellular microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/29488316","citation_count":13,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["PvRON5"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"23932940","id":"PMC_23932940","title":"Plasmodium falciparum rhoptry neck protein 5 peptides bind to human red blood cells and inhibit parasite invasion.","date":"2013","source":"Peptides","url":"https://pubmed.ncbi.nlm.nih.gov/23932940","citation_count":10,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["RON5"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"42379167","id":"PMC_42379167","title":"Structural basis for host membrane binding and remodeling by invading malaria parasites.","date":"2026","source":"Cell","url":"https://pubmed.ncbi.nlm.nih.gov/42379167","citation_count":0,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["PfRON5"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":8631,"output_tokens":2399,"usd":0.030939,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":7766,"output_tokens":3998,"usd":0.06939,"stage2_stop_reason":"end_turn"},"total_usd":0.100329,"stage1_batch_id":"msgbatch_01DisAaTypwmC8QwdMBuePHo","stage2_batch_id":"msgbatch_0184zxZTqxiEfdYYfPMfkqjb","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2026,\n      \"finding\": \"Cryo-EM structure of the endogenous P. falciparum moving junction complex (purified from invasion-stalled parasites) reveals a 1:1:1:1 assembly of PfAMA1, PfRON2, PfRON4, and PfRON5. PfRON5, together with PfRON2 and PfRON4, forms a large, basic platform inside the red blood cell that electrostatically engages the RBC membrane and wedges seven amphipathic helices deep into the lipid bilayer, indicating an active role in host-membrane remodeling during invasion.\",\n      \"method\": \"Cryo-EM structural determination of endogenous complex purified from invasion-stalled P. falciparum parasites\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — native complex purified directly from parasites, high-resolution cryo-EM structure with atomic-level mechanistic detail in a single rigorous study\",\n      \"pmids\": [\"42379167\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"PfRON5 was identified as a ~110 kDa protein expressed in merozoite and schizont stages. Anti-AMA1 antibody co-immunoprecipitates PfRON5 together with PfRON2 and PfRON4, placing PfRON5 as a component of the PfAMA1–RON complex associated with the moving junction during erythrocyte invasion.\",\n      \"method\": \"Co-immunoprecipitation with anti-AMA1 antibody, Western blot, stage-specific expression analysis\",\n      \"journal\": \"Gene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — single Co-IP experiment identifying complex membership, confirmed across multiple papers but original identification from single lab\",\n      \"pmids\": [\"21185360\", \"20228060\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"FCB-2\"}]\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Synthetic peptides derived from PfRON5 bind to human erythrocytes in a saturable manner sensitive to chymotrypsin and trypsin treatment of red blood cells, and inhibit P. falciparum merozoite invasion in vitro, demonstrating a direct functional role for PfRON5–erythrocyte interaction in invasion.\",\n      \"method\": \"Erythrocyte-binding assay with synthetic peptides, invasion inhibition assay\",\n      \"journal\": \"Peptides\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — direct functional assay (binding + inhibition) but single lab, single study, peptide-based approach\",\n      \"pmids\": [\"23932940\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"PvRON5 in P. vivax (VCG-1 strain) localizes to the rhoptry neck of late schizonts together with PvRON2 and PvRON4, undergoes proteolytic processing (detected as ~85 and ~30 kDa fragments in parasite lysate), and a recombinant fragment binds human reticulocytes with marked preference over normocytes, suggesting a direct role in host cell targeting.\",\n      \"method\": \"Immunofluorescence assay, Western blot of parasite lysate, recombinant protein reticulocyte-binding assay, polyclonal antibody detection\",\n      \"journal\": \"Malaria journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods (IFA localization, binding assay, proteolytic processing), single lab\",\n      \"pmids\": [\"25888962\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium vivax\", \"strain\": \"VCG-1\"}]\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"P. yoelii RON5 (PyRON5) localizes to the rhoptry neck of late schizont merozoites and to the rhoptry of sporozoites, partitions into water-insoluble membrane fractions without a predicted transmembrane domain, and co-immunoprecipitates with PyRON4, PyRON2, and PyAMA1 in late schizont extracts, indicating that PyRON5 associates with the moving junction complex indirectly via other MJ components.\",\n      \"method\": \"Indirect immunofluorescence assay, immunoelectron microscopy, co-immunoprecipitation, membrane fractionation, full-length cDNA sequencing\",\n      \"journal\": \"Parasitology international\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods (IFA, immuno-EM, Co-IP, fractionation) in a single focused study\",\n      \"pmids\": [\"25102354\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium yoelii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"In P. berghei sporozoites, RON5 forms a complex with RON2 and RON4 (shown by co-immunoprecipitation from oocyst-derived sporozoite extracts). Sporozoite stage-specific gene knockdown of RON5 significantly reduces sporozoite attachment ability and invasion of mosquito salivary glands. Unlike RON2 and RON4 (which reciprocally affect each other's trafficking to rhoptries), RON5 is independently transported to rhoptries in developing sporozoites.\",\n      \"method\": \"Co-immunoprecipitation from sporozoite extracts, sporozoite stage-specific gene knockdown, invasion and attachment assays\",\n      \"journal\": \"mSphere\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP demonstrating complex formation, combined with functional gene knockdown showing specific attachment/invasion phenotype and trafficking epistasis, single lab with multiple orthogonal methods\",\n      \"pmids\": [\"32817376\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium berghei\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"In P. berghei sporozoites, RON5 localizes to rhoptries by immunoelectron microscopy, whereas in merozoites it is at the rhoptry neck — demonstrating that the same protein distributes to different subcompartments of the rhoptry in the two invasive stages.\",\n      \"method\": \"Immuno-electron microscopy, transcriptional analysis of rhoptry genes in sporozoites\",\n      \"journal\": \"Frontiers in cellular and infection microbiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — immuno-EM localization with functional implication for stage-specific invasion, single lab\",\n      \"pmids\": [\"31552198\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium berghei\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"The R1 inhibitory peptide blocks PfAMA1 interaction with the PfRON complex (which includes PfRON5) by binding the PfAMA1 hydrophobic trough; this interaction occurs after merozoite reorientation and engagement of the actomyosin motor, placing AMA1–RON complex formation (and therefore RON5's participation in the complex) at a step that precedes rhoptry release.\",\n      \"method\": \"Peptide binding assay (R1 peptide competition), invasion inhibition assay with defined mechanistic staging\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — mechanistic staging by invasion inhibition and peptide competition assays, but RON5 contribution inferred as complex member rather than tested independently\",\n      \"pmids\": [\"20228060\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    }\n  ],\n  \"current_model\": \"PfRON5/PF3D7_0817700 is a rhoptry neck protein that forms a stoichiometric 1:1:1:1 complex with PfAMA1, PfRON2, and PfRON4 at the moving junction during erythrocyte invasion; its cryo-EM structure shows that together with RON2 and RON4 it creates a basic, amphipathic platform that electrostatically engages and remodels the host RBC membrane from the cytoplasmic face, while its surface-exposed peptides also directly contact the RBC exterior to facilitate invasion; in sporozoites (P. berghei) it forms the same RON2/RON4/RON5 complex, is independently trafficked to rhoptries, and is required for sporozoite attachment to and invasion of mosquito salivary glands.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"RON5 (PF3D7_0817700) is a rhoptry neck protein that functions as a core component of the moving junction complex that Plasmodium parasites assemble at the host-cell interface during invasion [#0, #1]. In P. falciparum, RON5 assembles in a 1:1:1:1 stoichiometric complex with AMA1, RON2, and RON4, and a cryo-EM structure of the endogenous complex shows that RON5, together with RON2 and RON4, forms a large, basic platform on the cytoplasmic (intracellular) face of the red blood cell that electrostatically engages the erythrocyte membrane and wedges amphipathic helices into the lipid bilayer, implicating RON5 in active remodeling of the host membrane during invasion [#0]. RON5 was originally identified as a ~110 kDa merozoite/schizont-stage protein that co-immunoprecipitates with AMA1 alongside RON2 and RON4 [#1], and its incorporation into the AMA1–RON complex occurs after merozoite reorientation and actomyosin-motor engagement, preceding rhoptry release [#7]. Beyond its intracellular platform role, RON5-derived peptides bind human erythrocytes in a protease-sensitive, saturable manner and inhibit merozoite invasion, indicating a direct RON5–erythrocyte contact that contributes to invasion [#2]. The protein's role extends across invasive stages and species: in P. berghei sporozoites RON5 forms a RON2/RON4/RON5 complex, is trafficked to rhoptries independently of RON2 and RON4, and is required for sporozoite attachment to and invasion of mosquito salivary glands [#5], and it relocates between the rhoptry neck (merozoites) and rhoptry body (sporozoites) in a stage-specific manner [#6]. Orthologs in P. vivax and P. yoelii show conserved rhoptry-neck localization, proteolytic processing, and host-cell (reticulocyte) binding preference [#3, #4].\",\n  \"teleology\": [\n    {\n      \"year\": 2010,\n      \"claim\": \"Establishing whether RON5 is part of the invasion machinery, this work identified RON5 as a stage-specific merozoite/schizont protein physically associated with the AMA1–RON moving junction complex.\",\n      \"evidence\": \"Anti-AMA1 co-immunoprecipitation, Western blot, and stage-specific expression analysis in P. falciparum FCB-2\",\n      \"pmids\": [\"21185360\", \"20228060\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single Co-IP does not define whether RON5 binds AMA1 directly or via other RON subunits\", \"No structural or stoichiometric information\", \"Functional necessity of RON5 not tested\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"FCB-2\"}]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"To place complex assembly within the invasion sequence, R1-peptide competition showed AMA1–RON complex formation (and thus RON5's participation) occurs after reorientation and motor engagement but before rhoptry release.\",\n      \"evidence\": \"R1 inhibitory peptide competition and staged invasion-inhibition assays in P. falciparum\",\n      \"pmids\": [\"20228060\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"RON5's contribution was inferred as a complex member, not tested independently\", \"Does not resolve RON5's specific molecular action at the junction\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Addressing whether RON5 directly engages the host cell, RON5-derived peptides were shown to bind erythrocytes in a saturable, protease-sensitive manner and block invasion, implicating a direct RON5–erythrocyte contact.\",\n      \"evidence\": \"Synthetic peptide erythrocyte-binding and invasion-inhibition assays in P. falciparum\",\n      \"pmids\": [\"23932940\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Peptide-based approach may not reflect native full-length protein behavior\", \"Erythrocyte receptor not identified\", \"Not confirmed with recombinant full-length RON5 or genetic depletion\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Testing conservation and mode of complex association, PyRON5 was shown to localize to rhoptries, partition into membrane fractions despite lacking a predicted transmembrane domain, and associate with the MJ complex indirectly through other components.\",\n      \"evidence\": \"IFA, immuno-EM, Co-IP, and membrane fractionation in P. yoelii\",\n      \"pmids\": [\"25102354\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism of membrane partitioning without a TM domain unresolved\", \"Which subunit directly recruits RON5 not defined\", \"No invasion phenotype from genetic depletion\"],\n      \"attribution\": [{\"species\": \"Plasmodium yoelii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Extending to P. vivax, PvRON5 was shown to localize to the rhoptry neck with RON2/RON4, undergo proteolytic processing, and preferentially bind reticulocytes, linking RON5 to host-cell tropism.\",\n      \"evidence\": \"IFA, Western blot, and recombinant reticulocyte-binding assay in P. vivax VCG-1\",\n      \"pmids\": [\"25888962\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional consequence of proteolytic processing unknown\", \"Reticulocyte receptor unidentified\", \"Binding preference not linked to invasion outcome genetically\"],\n      \"attribution\": [{\"species\": \"Plasmodium vivax\", \"strain\": \"VCG-1\"}]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"To explain stage-specific invasion behavior, immuno-EM revealed that RON5 occupies the rhoptry neck in merozoites but the rhoptry body in sporozoites, showing the same protein redistributes across invasive stages.\",\n      \"evidence\": \"Immuno-electron microscopy and rhoptry-gene transcriptional analysis in P. berghei\",\n      \"pmids\": [\"31552198\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional significance of subcompartment switch unresolved\", \"Trafficking signals directing the switch not defined\"],\n      \"attribution\": [{\"species\": \"Plasmodium berghei\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Providing direct genetic evidence of function, sporozoite-stage knockdown of RON5 impaired attachment to and invasion of mosquito salivary glands, and RON5 was shown to traffic to rhoptries independently of RON2/RON4.\",\n      \"evidence\": \"Reciprocal Co-IP from sporozoite extracts plus stage-specific knockdown with attachment/invasion assays in P. berghei\",\n      \"pmids\": [\"32817376\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular basis of the attachment defect not defined\", \"Trafficking signal enabling RON2/RON4-independent transport unknown\", \"Blood-stage genetic requirement for RON5 not tested here\"],\n      \"attribution\": [{\"species\": \"Plasmodium berghei\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"To define RON5's molecular action at the junction, cryo-EM of the endogenous P. falciparum complex resolved a 1:1:1:1 AMA1–RON2–RON4–RON5 assembly in which RON5, RON2, and RON4 build a basic platform that electrostatically engages and wedges amphipathic helices into the RBC membrane from the cytoplasmic face.\",\n      \"evidence\": \"Cryo-EM of endogenous complex purified from invasion-stalled P. falciparum parasites\",\n      \"pmids\": [\"42379167\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Which specific residues/helices of RON5 (versus RON2/RON4) insert into the membrane not individually dissected\", \"Dynamics of membrane remodeling during active invasion not captured\", \"Relationship between the intracellular platform and the surface-exposed RON5 peptide contacts not fully reconciled\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How RON5 crosses the erythrocyte membrane to establish an intracellular basic platform while also presenting surface-exposed peptides, and what specific molecular contribution RON5 makes distinct from RON2/RON4, remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No host receptor for RON5 identified\", \"RON5-specific contribution to membrane remodeling not isolated from other subunits\", \"Mechanism of RON5 insertion/translocation across the RBC membrane unknown\"],\n      \"attribution\": []\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0005102\", \"supporting_discovery_ids\": [2, 3]},\n      {\"term_id\": \"GO:0046982\", \"supporting_discovery_ids\": [0, 1, 4, 5]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0020008\", \"supporting_discovery_ids\": [1, 3, 4, 6]},\n      {\"term_id\": \"GO:0033644\", \"supporting_discovery_ids\": [0, 4]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0044409\", \"supporting_discovery_ids\": [0, 2, 5, 7]},\n      {\"term_id\": \"GO:0070152\", \"supporting_discovery_ids\": [0, 7]}\n    ],\n    \"complexes\": [\n      \"Moving junction complex: AMA1–RON2–RON4–RON5 (1:1:1:1 stoichiometry) in P. falciparum merozoites [#0, #1]\",\n      \"RON2–RON4–RON5 complex in P. berghei sporozoites [#5]\"\n    ],\n    \"partners\": [\n      \"PfAMA1 (via the AMA1–RON complex) [#0, #1, #7]\",\n      \"PfRON2 [#0, #1, #4, #5]\",\n      \"PfRON4 [#0, #1, #4, #5]\"\n    ],\n    \"other_free_text\": [\n      \"Expressed in merozoite and schizont stages as a ~110 kDa protein [#1]\",\n      \"Undergoes proteolytic processing (~85 and ~30 kDa fragments in P. vivax) [#3]\",\n      \"Partitions into water-insoluble membrane fractions despite lacking a predicted transmembrane domain (P. yoelii) [#4]\",\n      \"Trafficked to rhoptries independently of RON2 and RON4 in P. berghei sporozoites [#5]\",\n      \"Redistributes from rhoptry neck (merozoites) to rhoptry body (sporozoites) [#6]\",\n      \"Required for sporozoite attachment to and invasion of mosquito salivary glands (P. berghei) [#5]\",\n      \"Recombinant/synthetic RON5 fragments bind host cells: erythrocytes in P. falciparum [#2] and reticulocytes preferentially in P. vivax [#3]\"\n    ]\n  }\n}","audit_flag":null,"strains":[{"strain":"Pf3D7","gene_id":"PF3D7_0817700","name":null,"product":"rhoptry neck protein 5","uniprot_acc":null,"chromosome":null,"start_pos":null},{"strain":"PbANKA","gene_id":"PBANKA_0713100","name":null,"product":"rhoptry neck protein 5","uniprot_acc":null,"chromosome":null,"start_pos":null},{"strain":"PkH","gene_id":"PKNH_0502300","name":null,"product":"rhoptry neck protein 5, putative","uniprot_acc":null,"chromosome":null,"start_pos":null}],"gene_symbol":"RON5","evaluation":null}