{"gene":"PF3D7_1116000","run_date":"2026-09-08T12:51:28","timeline":{"discoveries":[{"year":2026,"finding":"Cryo-EM structure of the endogenous moving junction purified from invasion-stalled P. falciparum parasites reveals that PfRON4 assembles with PfAMA1, PfRON2, and PfRON5 in a 1:1:1:1 'sailboat-shaped' complex; PfRON2/4/5 form a large, basic platform inside the red blood cell that electrostatically engages the RBC membrane and wedges seven amphipathic helices deep into the bilayer, implying an active role for the complex (including PfRON4) in host-membrane remodeling.","method":"Cryo-EM structure determination of endogenous complex purified directly from invasion-stalled parasites; structural analysis of transmembrane anchoring and membrane-interaction surfaces","journal":"Cell","confidence":"High","confidence_rationale":"Tier 1 / Strong — endogenous complex purification combined with cryo-EM structure at defined resolution; multiple orthogonal structural and biochemical validations in a single rigorous study","pmids":["42379167"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2006,"finding":"PfRON4 co-immunoprecipitates with PfAMA1, establishing that the rhoptry neck protein PfRON4 physically interacts with the microneme protein AMA1 in P. falciparum merozoites; PfRON4 originates in the rhoptry necks, mirroring the TgRON4–TgAMA1 collaboration in Toxoplasma.","method":"Co-immunoprecipitation; immunofluorescence localization","journal":"Eukaryotic cell","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — direct Co-IP demonstrated in P. falciparum; consistent with independent replication in subsequent papers from multiple labs","pmids":["16835460"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2008,"finding":"Co-immunoprecipitation in P. falciparum confirmed that PfRON4 forms a complex with PfRON2 and PfAMA1, demonstrating conservation of the moving junction complex between T. gondii and P. falciparum.","method":"Co-immunoprecipitation","journal":"Parasitology international","confidence":"Medium","confidence_rationale":"Tier 3 / Strong — single Co-IP method but independently replicated across multiple labs and species","pmids":["18952195"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2010,"finding":"The R1 peptide, which binds the PfAMA1 hydrophobic trough, blocks the interaction between PfAMA1 and the PfRON complex (containing PfRON4); this association occurs after merozoite reorientation and engagement of the actomyosin motor, placing PfRON4-containing complex formation at a defined step preceding rhoptry contents release.","method":"Peptide inhibition assay; invasion timing assays; co-immunoprecipitation competition","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods (peptide inhibition, timed invasion assays, Co-IP disruption) in a single study from one lab","pmids":["20228060"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2011,"finding":"In P. berghei, RON4 is required for merozoite invasion of erythrocytes and also for sporozoite invasion of hepatocytes, and RON4 acts independently of AMA1 in the sporozoite context (RON4 knockdown impairs sporozoite hepatocyte invasion while AMA1 is dispensable for sporozoite TJ assembly).","method":"Genetic loss-of-function (gene knockdown/knockout) in P. berghei; invasion assays in erythrocytes and hepatocytes; immunofluorescence","journal":"Cell host & microbe","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean genetic loss-of-function with specific phenotypic readouts in two distinct host cell types, replicated across parasite stages; epistasis established between RON4 and AMA1","pmids":["22177563"],"is_preprint":false,"attribution":[{"species":"Plasmodium berghei","strain":""}]},{"year":2011,"finding":"PfRON3 co-immunoprecipitates with PfRON4 (and PfRON2) but not with PfAMA1, indicating PfRON4 participates in a second RON complex (PfRON2/3/4) distinct from the canonical moving junction complex (PfRON2/4/5/AMA1).","method":"Co-immunoprecipitation","journal":"Parasitology international","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single Co-IP from one lab; PfRON4 participation inferred from pull-down of PfRON3 partner","pmids":["21237287"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2012,"finding":"Super-resolution imaging during merozoite invasion places the actin ring posterior to, and not concentric with, PfRON4 at the tight junction, indicating that PfRON4 marks the adhesion site while dynamic actin microfilaments form a distinct, more posterior zone of traction.","method":"Super-resolution fluorescence microscopy (live imaging and fixed); co-localization with RON4 as junction marker","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct super-resolution localization experiment with functional interpretation; single study but rigorous imaging with multiple controls","pmids":["22389687"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""},{"species":"Plasmodium berghei","strain":""}]},{"year":2014,"finding":"In P. yoelii sporozoites, RON2 and RON4 are lost following rhoptry discharge during sporozoite entry into hepatocytes; rhoptry discharge of RON4 occurs only when host membrane protein CD81 is present, demonstrating that CD81 is required for productive sporozoite invasion upstream of RON4 secretion.","method":"Transgenic parasites expressing fluorescent RON4; live imaging of sporozoite entry; CD81-deficient vs. wild-type hepatocyte comparison","journal":"Cellular microbiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct fluorescent reporter experiment linking CD81 requirement to RON4 secretion; single lab, two orthogonal readouts (imaging + genetic host-cell variation)","pmids":["24798694"],"is_preprint":false,"attribution":[{"species":"Plasmodium yoelii","strain":""}]},{"year":2018,"finding":"Immunoprecipitation followed by mass spectrometry identified that PfRON4 interacts with SURFIN4.2 and GLURP to form the SURGE complex in the rhoptry neck of P. falciparum merozoites, implicating PfRON4 in a broader protein assembly at the merozoite apex–RBC contact site.","method":"Immunoprecipitation followed by mass spectrometry; immunofluorescence co-localization","journal":"PloS one","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single IP-MS study from one lab; functional role of PfRON4 within the SURGE complex not directly tested","pmids":["30092030"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2019,"finding":"Immuno-electron microscopy in P. berghei sporozoites shows that RON4 localizes to rhoptries (throughout the organelle rather than exclusively at the neck as in merozoites), demonstrating a stage-specific redistribution of RON4 subcellular localization.","method":"Immuno-electron microscopy; immunofluorescence assay in sporozoites","journal":"Frontiers in cellular and infection microbiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct immunoelectron microscopy localizing RON4 in sporozoites; single lab but orthogonal IFA and IEM methods","pmids":["31552198"],"is_preprint":false,"attribution":[{"species":"Plasmodium berghei","strain":""}]},{"year":2020,"finding":"Co-immunoprecipitation from P. berghei oocyst-derived sporozoite extracts demonstrated that RON2, RON4, and RON5 form a protein complex in sporozoites. Sporozoite stage-specific gene knockdown of RON4 significantly reduced sporozoite attachment to salivary gland cells and impaired salivary gland invasion. Reciprocal trafficking experiments showed that RON2 and RON4 mutually affect each other's stability and trafficking to rhoptries in developing sporozoites, while RON5 is independently transported.","method":"Co-immunoprecipitation from sporozoite extracts; sporozoite stage-specific gene knockdown (P. berghei); attachment and invasion assays; fluorescence microscopy of rhoptry trafficking","journal":"mSphere","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP combined with stage-specific genetic knockdown, attachment assays, and trafficking analysis; multiple orthogonal methods in one rigorous study","pmids":["32817376"],"is_preprint":false,"attribution":[{"species":"Plasmodium berghei","strain":""}]},{"year":2022,"finding":"Using DiCre-mediated conditional deletion in P. berghei, loss of RON4 in sporozoites impaired colonization of mosquito salivary glands and invasion of mammalian hepatocytes without affecting transcellular migration. 3D electron microscopy showed that absence of a functional AMA1-RON complex (including RON4) altered the morphology of the entry junction and caused epithelial cell damage, demonstrating that the AMA1-RON4-containing complex is required for efficient and safe host cell entry across transmission stages.","method":"DiCre-mediated conditional gene deletion in P. berghei; salivary gland colonization assay; hepatocyte invasion assay; 3D electron microscopy of entry junctions","journal":"PLoS pathogens","confidence":"High","confidence_rationale":"Tier 2 / Strong — conditional genetic deletion with specific stage phenotype, complemented by ultrastructural 3D EM of junction morphology; multiple orthogonal methods and rigorous controls","pmids":["35731833"],"is_preprint":false,"attribution":[{"species":"Plasmodium berghei","strain":""}]},{"year":2023,"finding":"Sporozoite stage-specific knockdown of RON4 in P. berghei demonstrated that RON4 is required for traversal of sinusoidal cells and infection of hepatocytes in vivo; in vitro experiments showed that secreted RON4 mediates sporozoite adhesion to hepatocytes and is required for the onset of gliding motility (attachment to substrate), establishing RON4 as having multiple sequential functions during liver-stage infection.","method":"Sporozoite stage-specific gene silencing in P. berghei; in vivo intravenous inoculation into mice; in vitro hepatoma cell infection assays; in vitro motility assays","journal":"mSphere","confidence":"High","confidence_rationale":"Tier 2 / Strong — stage-specific genetic knockdown with in vivo and multiple in vitro functional readouts (invasion, adhesion, motility) providing mechanistic dissection across sequential steps","pmids":["37272704"],"is_preprint":false,"attribution":[{"species":"Plasmodium berghei","strain":""}]},{"year":2023,"finding":"Receptor-ligand binding assays with P. falciparum RON4-derived conserved peptides identified specific regions (PfRON4 residues 800–819 and 860–879) that bind erythrocytes via protease-sensitive protein receptors and HepG2 hepatocyte membranes via heparin- and chondroitin sulphate proteoglycan-type receptors; peptides corresponding to these regions inhibited in vitro merozoite invasion.","method":"Peptide synthesis; erythrocyte and HepG2 binding assays; enzyme treatment of host cells (trypsin, chymotrypsin, heparinase I, chondroitinase ABC); in vitro invasion inhibition assays; surface plasmon resonance (Kd determination)","journal":"International journal of medical microbiology : IJMM","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal binding and inhibition assays with enzymatic receptor characterization; single lab but SPR quantification and functional invasion inhibition","pmids":["37030083"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2009,"finding":"Quantitative real-time PCR of synchronized P. falciparum cultures showed that PfRON4 gene transcription peaks at the mature schizont stage (36–40 hours post-invasion), consistent with its protein's role in erythrocyte invasion.","method":"Real-time quantitative PCR of synchronized P. falciparum parasites","journal":"Zhongguo ji sheng chong xue yu ji sheng chong bing za zhi","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single transcriptional profiling method, no protein-level mechanistic follow-up in this paper","pmids":["19852359"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2008,"finding":"PyP140/RON4 in P. yoelii localizes to the apical end of merozoites (rhoptries or micronemes) and forms a complex with AMA1; however, the conserved cysteine-rich domain, when expressed recombinantly, failed to elicit growth-inhibitory antibodies in mice, indicating this domain alone is not a protective immunogen.","method":"Monoclonal antibody screening of cDNA expression library; IFA localization; immunoprecipitation with AMA1; recombinant protein immunization and challenge in BALB/c mice","journal":"Infection and immunity","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — direct immunoprecipitation demonstrating AMA1 association; in vivo immunization challenge provides functional (negative) readout; single lab","pmids":["18710865"],"is_preprint":false,"attribution":[{"species":"Plasmodium yoelii","strain":"YM"}]}],"current_model":"PfRON4 (PF3D7_1116000) is a rhoptry neck protein that is secreted during invasion and assembles with PfRON2 and PfRON5 into a stable complex; cryo-EM of this endogenous complex reveals a 1:1:1:1 sailboat-shaped assembly with PfAMA1 in which PfRON2/4/5 form a basic intracellular platform that electrostatically engages and remodels the red blood cell membrane, while on the host-cell exterior PfAMA1 contacts the RBC membrane to stabilize the moving junction; PfRON4 also participates in a second RON complex (with RON2/3) and in the SURGE complex (with SURFIN4.2 and GLURP); in sporozoites PfRON4 is present throughout the rhoptry, forms a complex with RON2 and RON5, reciprocally stabilizes RON2 trafficking to rhoptries, mediates sporozoite attachment to substrates and host cells, and is required for salivary gland colonization, sinusoidal cell traversal, and hepatocyte invasion independently of AMA1."},"narrative":{"mechanistic_narrative":"RON4 (PF3D7_1116000) is a rhoptry neck protein that functions as a core structural component of the moving junction, the ring-shaped adhesion interface through which apicomplexan parasites enter host cells [PMID:16835460, PMID:22389687]. During P. falciparum merozoite invasion of erythrocytes, RON4 is secreted from the rhoptry necks and assembles with RON2 and RON5 and the microneme protein AMA1; cryo-EM of the endogenous invasion-stalled complex resolves a 1:1:1:1 'sailboat-shaped' assembly in which the RON2/4/5 subcomplex forms a basic intracellular platform that electrostatically engages the erythrocyte membrane and drives active host-membrane remodeling, while AMA1 stabilizes the junction from the host-cell exterior [PMID:42379167]. RON4-AMA1 association occurs after merozoite reorientation and actomyosin motor engagement, placing complex assembly at a defined step preceding rhoptry-content release, and RON4 marks the adhesion ring itself, distinct from a more posterior actin traction zone [PMID:20228060, PMID:22389687]. RON4 additionally participates in a second RON2/3/4 complex lacking AMA1 and in the rhoptry-neck SURGE complex with SURFIN4.2 and GLURP [PMID:21237287, PMID:30092030]. Beyond the blood stage, RON4 acts across transmission stages: in P. berghei and P. yoelii sporozoites it redistributes throughout the rhoptry, forms a RON2/RON4/RON5 complex in which RON4 and RON2 reciprocally stabilize each other's trafficking, and is required for salivary gland colonization, sinusoidal cell traversal, sporozoite attachment and gliding onset, and hepatocyte invasion independently of AMA1 [PMID:22177563, PMID:31552198, PMID:32817376, PMID:35731833, PMID:37272704]. Conserved RON4 peptide regions bind erythrocytes via protease-sensitive receptors and hepatocytes via proteoglycan-type receptors and inhibit merozoite invasion, indicating direct host-cell recognition activity [PMID:37030083].","teleology":[{"year":2006,"claim":"Establishing that RON4 physically links the rhoptry neck to the microneme protein AMA1 defined it as a candidate structural bridge of the invasion junction in P. falciparum, extending a mechanism first seen in Toxoplasma.","evidence":"Co-immunoprecipitation and immunofluorescence localization in P. falciparum merozoites","pmids":["16835460"],"confidence":"Medium","gaps":["Direct interaction interface not mapped","Stoichiometry and additional partners unresolved","Functional consequence of the interaction not tested"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2008,"claim":"Demonstrating that RON4 co-purifies with RON2 and AMA1 confirmed a multi-protein moving-junction complex conserved between Toxoplasma and Plasmodium, moving RON4 from a bilateral interactor to a member of a defined assembly.","evidence":"Co-immunoprecipitation in P. falciparum; in P. yoelii, PyP140/RON4 localized apically and co-immunoprecipitated with AMA1, while its recombinant cysteine-rich domain failed to elicit protective antibodies","pmids":["18952195","18710865"],"confidence":"Medium","gaps":["Complex architecture and subunit contacts unknown","Whether all subunits associate simultaneously not resolved","Protective epitopes of RON4 not identified"],"attribution":[{"species":"Plasmodium falciparum","strain":""},{"species":"Plasmodium yoelii","strain":"YM"}]},{"year":2009,"claim":"Timing RON4 transcription to the mature schizont stage tied its expression to the point in the cycle when invasion machinery is assembled.","evidence":"Quantitative RT-PCR of synchronized P. falciparum cultures","pmids":["19852359"],"confidence":"Low","gaps":["Transcript-only readout with no protein-level follow-up","Does not address post-transcriptional regulation or timing of secretion"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2010,"claim":"Placing RON4-AMA1 complex formation after motor engagement and before rhoptry release ordered the junction assembly within the invasion sequence, and showed the AMA1 hydrophobic trough is required for the interaction.","evidence":"R1 peptide inhibition, timed invasion assays, and Co-IP competition in P. falciparum","pmids":["20228060"],"confidence":"Medium","gaps":["Which RON subunit contacts the AMA1 trough not resolved","Kinetics of assembly not quantified"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2011,"claim":"Genetic loss-of-function established RON4 as functionally essential for both merozoite erythrocyte invasion and sporozoite hepatocyte invasion, and revealed AMA1-independence in the sporozoite context.","evidence":"Gene knockdown/knockout in P. berghei with invasion assays in erythrocytes and hepatocytes; RON3 Co-IP in P. falciparum defined a second RON2/3/4 complex distinct from the AMA1-containing junction","pmids":["22177563","21237287"],"confidence":"High","gaps":["Molecular basis of AMA1-independence in sporozoites unknown","Function of the RON2/3/4 complex (Low-confidence, single Co-IP) not tested","How RON4 substitutes for the AMA1 anchor unresolved"],"attribution":[{"species":"Plasmodium berghei","strain":""},{"species":"Plasmodium falciparum","strain":""}]},{"year":2012,"claim":"Super-resolution imaging separated the RON4-marked adhesion ring from a posterior actin traction zone, refining the physical model of how the junction couples adhesion to force generation.","evidence":"Super-resolution fluorescence microscopy of invading merozoites in P. falciparum and P. berghei","pmids":["22389687"],"confidence":"Medium","gaps":["Molecular coupling between the RON4 ring and actin not defined","Dynamics of ring constriction not measured"],"attribution":[{"species":"Plasmodium falciparum","strain":""},{"species":"Plasmodium berghei","strain":""}]},{"year":2014,"claim":"Linking RON4 rhoptry discharge to host CD81 placed a host-membrane requirement upstream of RON4 secretion during sporozoite entry into hepatocytes.","evidence":"Fluorescent RON4 reporter live imaging in P. yoelii sporozoites comparing CD81-deficient and wild-type hepatocytes","pmids":["24798694"],"confidence":"Medium","gaps":["Mechanism by which CD81 triggers rhoptry discharge unknown","Whether RON4 directly senses CD81 not tested"],"attribution":[{"species":"Plasmodium yoelii","strain":""}]},{"year":2018,"claim":"Identifying RON4 within the SURGE complex broadened its interaction network at the merozoite apex beyond the canonical RON/AMA1 junction.","evidence":"IP-mass spectrometry and immunofluorescence co-localization in P. falciparum merozoites","pmids":["30092030"],"confidence":"Low","gaps":["Functional role of RON4 within SURGE not directly tested","Single IP-MS study from one lab without reciprocal validation"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2020,"claim":"Demonstrating a sporozoite RON2/RON4/RON5 complex with reciprocal RON2-RON4 trafficking stabilization and a role in salivary gland attachment established RON4's stage-specific complex biology and interdependence.","evidence":"Co-IP from P. berghei sporozoite extracts, stage-specific knockdown, attachment/invasion assays, and rhoptry trafficking imaging","pmids":["32817376"],"confidence":"High","gaps":["Structural basis of reciprocal stabilization unknown","Why RON5 traffics independently not explained"],"attribution":[{"species":"Plasmodium berghei","strain":""}]},{"year":2022,"claim":"Conditional deletion and 3D EM tied RON4-containing junction integrity to normal junction morphology and to preventing host epithelial damage, showing the complex ensures efficient and non-destructive entry across transmission stages.","evidence":"DiCre conditional deletion in P. berghei with salivary gland colonization, hepatocyte invasion assays, and 3D electron microscopy of entry junctions","pmids":["35731833"],"confidence":"High","gaps":["Molecular cause of aberrant junction morphology not resolved","Whether epithelial damage is a direct or downstream consequence unclear"],"attribution":[{"species":"Plasmodium berghei","strain":""}]},{"year":2023,"claim":"Dissecting sequential sporozoite functions and identifying host-binding peptide regions showed that secreted RON4 mediates adhesion, gliding onset, cell traversal, and invasion via defined receptor interactions.","evidence":"Stage-specific knockdown with in vivo and in vitro infection, adhesion, and motility assays in P. berghei; RON4 conserved-peptide (residues 800-819, 860-879) binding to erythrocyte protease-sensitive and hepatocyte proteoglycan receptors with SPR and invasion inhibition in P. falciparum","pmids":["37272704","37030083"],"confidence":"High","gaps":["Identity of the host receptor proteins not determined","How a rhoptry-neck protein mediates surface adhesion before discharge unresolved","Structural basis of peptide-receptor binding unknown"],"attribution":[{"species":"Plasmodium berghei","strain":""},{"species":"Plasmodium falciparum","strain":""}]},{"year":2026,"claim":"The cryo-EM structure of the endogenous moving junction defined RON4 as part of a basic RON2/4/5 platform that electrostatically engages and actively remodels the host membrane, elevating the complex from a passive anchor to an active membrane-remodeling machine.","evidence":"Cryo-EM of the endogenous invasion-stalled moving-junction complex purified from P. falciparum with structural analysis of transmembrane anchoring and membrane-interaction surfaces","pmids":["42379167"],"confidence":"High","gaps":["RON4-specific contribution to the seven amphipathic helices not isolated","Dynamics of membrane remodeling not captured","Conformational changes during junction progression not resolved"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":null,"claim":"The molecular mechanism by which RON4 discriminates and engages host receptors, and its individual contribution to membrane remodeling versus its RON2/RON5 partners, remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["Host receptor proteins bound by RON4 peptides not identified","RON4-specific vs. complex-level membrane-remodeling function not separated","How the same protein serves AMA1-dependent (merozoite) and AMA1-independent (sporozoite) invasion is unexplained"],"attribution":[]}],"mechanism_profile":{"molecular_activity":[],"localization":[],"pathway":[],"complexes":["Moving junction complex (RON2/RON4/RON5/AMA1)","RON2/RON3/RON4 complex","SURGE complex (RON4/SURFIN4.2/GLURP)","Sporozoite RON2/RON4/RON5 complex"],"partners":["AMA1","RON2","RON5","RON3","SURFIN4.2","GLURP"],"other_free_text":["Transcription peaks at mature schizont stage (36-40 h post-invasion) in P. falciparum [#14]","Secreted from rhoptry necks; discharge depends on host CD81 in P. yoelii sporozoites [#7]","RON4 and RON2 reciprocally stabilize each other's trafficking to rhoptries; RON5 traffics independently in P. berghei sporozoites [#10]","Conserved peptide regions (residues 800-819, 860-879) bind erythrocyte protease-sensitive receptors and hepatocyte proteoglycan-type receptors [#13]","RON2/4/5 platform wedges seven amphipathic helices into the RBC bilayer and electrostatically remodels host membrane [#0]","Functions in sporozoite salivary gland colonization, sinusoidal cell traversal, gliding onset, and hepatocyte invasion, AMA1-independently [#4, #11, #12]"]}},"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":["RON4"],"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":["RON4","PfRON4"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"16835460","id":"PMC_16835460","title":"Plasmodium falciparum AMA1 binds a rhoptry neck protein homologous to TgRON4, a component of the moving junction in Toxoplasma gondii.","date":"2006","source":"Eukaryotic cell","url":"https://pubmed.ncbi.nlm.nih.gov/16835460","citation_count":127,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["PfRON4"],"competing_organism_flag":true,"competing_organism_match":"Toxoplasma","competing_organism_only":false},{"pmid":"22177563","id":"PMC_22177563","title":"Independent roles of apical membrane antigen 1 and rhoptry neck proteins during host cell invasion by apicomplexa.","date":"2011","source":"Cell host & microbe","url":"https://pubmed.ncbi.nlm.nih.gov/22177563","citation_count":101,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["RON4"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"22389687","id":"PMC_22389687","title":"Spatial localisation of actin filaments across developmental stages of the malaria parasite.","date":"2012","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/22389687","citation_count":62,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["rhoptry neck protein 4"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"28089547","id":"PMC_28089547","title":"Antibody profiles to wheat germ cell-free system synthesized Plasmodium falciparum proteins correlate with protection from symptomatic malaria in Uganda.","date":"2017","source":"Vaccine","url":"https://pubmed.ncbi.nlm.nih.gov/28089547","citation_count":43,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["RON4"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"35731833","id":"PMC_35731833","title":"The AMA1-RON complex drives Plasmodium sporozoite invasion in the mosquito and mammalian hosts.","date":"2022","source":"PLoS 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international","url":"https://pubmed.ncbi.nlm.nih.gov/25102354","citation_count":17,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["RON4","PyRON4"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"27756311","id":"PMC_27756311","title":"Size polymorphism and low sequence diversity in the locus encoding the Plasmodium vivax rhoptry neck protein 4 (PvRON4) in Colombian isolates.","date":"2016","source":"Malaria journal","url":"https://pubmed.ncbi.nlm.nih.gov/27756311","citation_count":15,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["RON4","rhoptry neck protein 4","PvRON4"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"24093777","id":"PMC_24093777","title":"Annotation and characterization of the Plasmodium vivax rhoptry neck protein 4 (PvRON4).","date":"2013","source":"Malaria journal","url":"https://pubmed.ncbi.nlm.nih.gov/24093777","citation_count":15,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["RON4","rhoptry neck protein 4","PfRON4","PkRON4","PvRON4"],"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":["RON4"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"30092030","id":"PMC_30092030","title":"SURGE complex of Plasmodium falciparum in the rhoptry-neck (SURFIN4.2-RON4-GLURP) contributes to merozoite invasion.","date":"2018","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/30092030","citation_count":14,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["RON4","rhoptry neck protein 4"],"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":["RON4","PvRON4"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"25495792","id":"PMC_25495792","title":"PfRON3 is an erythrocyte-binding protein and a potential blood-stage vaccine candidate antigen.","date":"2014","source":"Malaria journal","url":"https://pubmed.ncbi.nlm.nih.gov/25495792","citation_count":11,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["PfRON4"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"27348424","id":"PMC_27348424","title":"Plasmodium falciparum Rab1A Localizes to Rhoptries in Schizonts.","date":"2016","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/27348424","citation_count":9,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["RON4"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"33886601","id":"PMC_33886601","title":"Suitability of IgG responses to multiple Plasmodium falciparum antigens as markers of transmission intensity and pattern.","date":"2021","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/33886601","citation_count":8,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["RON4"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"30290224","id":"PMC_30290224","title":"Plasmodium RON12 localizes to the rhoptry body in sporozoites.","date":"2018","source":"Parasitology international","url":"https://pubmed.ncbi.nlm.nih.gov/30290224","citation_count":7,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["RON4"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"37197657","id":"PMC_37197657","title":"High opsonic phagocytosis activity and growth inhibition of merozoites are associated with RON4 antibody levels and protect against febrile malaria in Ghanaian children.","date":"2023","source":"Frontiers in immunology","url":"https://pubmed.ncbi.nlm.nih.gov/37197657","citation_count":5,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["RON4"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"37272704","id":"PMC_37272704","title":"Rhoptry neck protein 4 plays important roles during Plasmodium sporozoite infection of the mammalian liver.","date":"2023","source":"mSphere","url":"https://pubmed.ncbi.nlm.nih.gov/37272704","citation_count":3,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["RON4","rhoptry neck protein 4"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"37030083","id":"PMC_37030083","title":"Plasmodium falciparum rhoptry neck protein 4 has conserved regions mediating interactions with receptors on human erythrocytes and hepatocyte membrane.","date":"2023","source":"International journal of medical microbiology : IJMM","url":"https://pubmed.ncbi.nlm.nih.gov/37030083","citation_count":2,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["RON4","rhoptry neck protein 4","PfRON4"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"19852359","id":"PMC_19852359","title":"[Transcription profile of PfRON4 gene in Plasmodium falciparum erythrocytic stage].","date":"2009","source":"Zhongguo ji sheng chong xue yu ji sheng chong bing za zhi = Chinese journal of parasitology & parasitic diseases","url":"https://pubmed.ncbi.nlm.nih.gov/19852359","citation_count":2,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["PfRON4"],"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":["PfRON4"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":18566,"output_tokens":4577,"usd":0.062177,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":10927,"output_tokens":5223,"usd":0.092605,"stage2_stop_reason":"end_turn"},"total_usd":0.154782,"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 moving junction purified from invasion-stalled P. falciparum parasites reveals that PfRON4 assembles with PfAMA1, PfRON2, and PfRON5 in a 1:1:1:1 'sailboat-shaped' complex; PfRON2/4/5 form a large, basic platform inside the red blood cell that electrostatically engages the RBC membrane and wedges seven amphipathic helices deep into the bilayer, implying an active role for the complex (including PfRON4) in host-membrane remodeling.\",\n      \"method\": \"Cryo-EM structure determination of endogenous complex purified directly from invasion-stalled parasites; structural analysis of transmembrane anchoring and membrane-interaction surfaces\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — endogenous complex purification combined with cryo-EM structure at defined resolution; multiple orthogonal structural and biochemical validations in a single rigorous study\",\n      \"pmids\": [\"42379167\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"PfRON4 co-immunoprecipitates with PfAMA1, establishing that the rhoptry neck protein PfRON4 physically interacts with the microneme protein AMA1 in P. falciparum merozoites; PfRON4 originates in the rhoptry necks, mirroring the TgRON4–TgAMA1 collaboration in Toxoplasma.\",\n      \"method\": \"Co-immunoprecipitation; immunofluorescence localization\",\n      \"journal\": \"Eukaryotic cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — direct Co-IP demonstrated in P. falciparum; consistent with independent replication in subsequent papers from multiple labs\",\n      \"pmids\": [\"16835460\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Co-immunoprecipitation in P. falciparum confirmed that PfRON4 forms a complex with PfRON2 and PfAMA1, demonstrating conservation of the moving junction complex between T. gondii and P. falciparum.\",\n      \"method\": \"Co-immunoprecipitation\",\n      \"journal\": \"Parasitology international\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Strong — single Co-IP method but independently replicated across multiple labs and species\",\n      \"pmids\": [\"18952195\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"The R1 peptide, which binds the PfAMA1 hydrophobic trough, blocks the interaction between PfAMA1 and the PfRON complex (containing PfRON4); this association occurs after merozoite reorientation and engagement of the actomyosin motor, placing PfRON4-containing complex formation at a defined step preceding rhoptry contents release.\",\n      \"method\": \"Peptide inhibition assay; invasion timing assays; co-immunoprecipitation competition\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods (peptide inhibition, timed invasion assays, Co-IP disruption) in a single study from one lab\",\n      \"pmids\": [\"20228060\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"In P. berghei, RON4 is required for merozoite invasion of erythrocytes and also for sporozoite invasion of hepatocytes, and RON4 acts independently of AMA1 in the sporozoite context (RON4 knockdown impairs sporozoite hepatocyte invasion while AMA1 is dispensable for sporozoite TJ assembly).\",\n      \"method\": \"Genetic loss-of-function (gene knockdown/knockout) in P. berghei; invasion assays in erythrocytes and hepatocytes; immunofluorescence\",\n      \"journal\": \"Cell host & microbe\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean genetic loss-of-function with specific phenotypic readouts in two distinct host cell types, replicated across parasite stages; epistasis established between RON4 and AMA1\",\n      \"pmids\": [\"22177563\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium berghei\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"PfRON3 co-immunoprecipitates with PfRON4 (and PfRON2) but not with PfAMA1, indicating PfRON4 participates in a second RON complex (PfRON2/3/4) distinct from the canonical moving junction complex (PfRON2/4/5/AMA1).\",\n      \"method\": \"Co-immunoprecipitation\",\n      \"journal\": \"Parasitology international\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single Co-IP from one lab; PfRON4 participation inferred from pull-down of PfRON3 partner\",\n      \"pmids\": [\"21237287\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Super-resolution imaging during merozoite invasion places the actin ring posterior to, and not concentric with, PfRON4 at the tight junction, indicating that PfRON4 marks the adhesion site while dynamic actin microfilaments form a distinct, more posterior zone of traction.\",\n      \"method\": \"Super-resolution fluorescence microscopy (live imaging and fixed); co-localization with RON4 as junction marker\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct super-resolution localization experiment with functional interpretation; single study but rigorous imaging with multiple controls\",\n      \"pmids\": [\"22389687\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}, {\"species\": \"Plasmodium berghei\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"In P. yoelii sporozoites, RON2 and RON4 are lost following rhoptry discharge during sporozoite entry into hepatocytes; rhoptry discharge of RON4 occurs only when host membrane protein CD81 is present, demonstrating that CD81 is required for productive sporozoite invasion upstream of RON4 secretion.\",\n      \"method\": \"Transgenic parasites expressing fluorescent RON4; live imaging of sporozoite entry; CD81-deficient vs. wild-type hepatocyte comparison\",\n      \"journal\": \"Cellular microbiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct fluorescent reporter experiment linking CD81 requirement to RON4 secretion; single lab, two orthogonal readouts (imaging + genetic host-cell variation)\",\n      \"pmids\": [\"24798694\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium yoelii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Immunoprecipitation followed by mass spectrometry identified that PfRON4 interacts with SURFIN4.2 and GLURP to form the SURGE complex in the rhoptry neck of P. falciparum merozoites, implicating PfRON4 in a broader protein assembly at the merozoite apex–RBC contact site.\",\n      \"method\": \"Immunoprecipitation followed by mass spectrometry; immunofluorescence co-localization\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single IP-MS study from one lab; functional role of PfRON4 within the SURGE complex not directly tested\",\n      \"pmids\": [\"30092030\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Immuno-electron microscopy in P. berghei sporozoites shows that RON4 localizes to rhoptries (throughout the organelle rather than exclusively at the neck as in merozoites), demonstrating a stage-specific redistribution of RON4 subcellular localization.\",\n      \"method\": \"Immuno-electron microscopy; immunofluorescence assay in sporozoites\",\n      \"journal\": \"Frontiers in cellular and infection microbiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct immunoelectron microscopy localizing RON4 in sporozoites; single lab but orthogonal IFA and IEM methods\",\n      \"pmids\": [\"31552198\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium berghei\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Co-immunoprecipitation from P. berghei oocyst-derived sporozoite extracts demonstrated that RON2, RON4, and RON5 form a protein complex in sporozoites. Sporozoite stage-specific gene knockdown of RON4 significantly reduced sporozoite attachment to salivary gland cells and impaired salivary gland invasion. Reciprocal trafficking experiments showed that RON2 and RON4 mutually affect each other's stability and trafficking to rhoptries in developing sporozoites, while RON5 is independently transported.\",\n      \"method\": \"Co-immunoprecipitation from sporozoite extracts; sporozoite stage-specific gene knockdown (P. berghei); attachment and invasion assays; fluorescence microscopy of rhoptry trafficking\",\n      \"journal\": \"mSphere\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP combined with stage-specific genetic knockdown, attachment assays, and trafficking analysis; multiple orthogonal methods in one rigorous study\",\n      \"pmids\": [\"32817376\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium berghei\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Using DiCre-mediated conditional deletion in P. berghei, loss of RON4 in sporozoites impaired colonization of mosquito salivary glands and invasion of mammalian hepatocytes without affecting transcellular migration. 3D electron microscopy showed that absence of a functional AMA1-RON complex (including RON4) altered the morphology of the entry junction and caused epithelial cell damage, demonstrating that the AMA1-RON4-containing complex is required for efficient and safe host cell entry across transmission stages.\",\n      \"method\": \"DiCre-mediated conditional gene deletion in P. berghei; salivary gland colonization assay; hepatocyte invasion assay; 3D electron microscopy of entry junctions\",\n      \"journal\": \"PLoS pathogens\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — conditional genetic deletion with specific stage phenotype, complemented by ultrastructural 3D EM of junction morphology; multiple orthogonal methods and rigorous controls\",\n      \"pmids\": [\"35731833\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium berghei\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Sporozoite stage-specific knockdown of RON4 in P. berghei demonstrated that RON4 is required for traversal of sinusoidal cells and infection of hepatocytes in vivo; in vitro experiments showed that secreted RON4 mediates sporozoite adhesion to hepatocytes and is required for the onset of gliding motility (attachment to substrate), establishing RON4 as having multiple sequential functions during liver-stage infection.\",\n      \"method\": \"Sporozoite stage-specific gene silencing in P. berghei; in vivo intravenous inoculation into mice; in vitro hepatoma cell infection assays; in vitro motility assays\",\n      \"journal\": \"mSphere\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — stage-specific genetic knockdown with in vivo and multiple in vitro functional readouts (invasion, adhesion, motility) providing mechanistic dissection across sequential steps\",\n      \"pmids\": [\"37272704\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium berghei\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Receptor-ligand binding assays with P. falciparum RON4-derived conserved peptides identified specific regions (PfRON4 residues 800–819 and 860–879) that bind erythrocytes via protease-sensitive protein receptors and HepG2 hepatocyte membranes via heparin- and chondroitin sulphate proteoglycan-type receptors; peptides corresponding to these regions inhibited in vitro merozoite invasion.\",\n      \"method\": \"Peptide synthesis; erythrocyte and HepG2 binding assays; enzyme treatment of host cells (trypsin, chymotrypsin, heparinase I, chondroitinase ABC); in vitro invasion inhibition assays; surface plasmon resonance (Kd determination)\",\n      \"journal\": \"International journal of medical microbiology : IJMM\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal binding and inhibition assays with enzymatic receptor characterization; single lab but SPR quantification and functional invasion inhibition\",\n      \"pmids\": [\"37030083\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Quantitative real-time PCR of synchronized P. falciparum cultures showed that PfRON4 gene transcription peaks at the mature schizont stage (36–40 hours post-invasion), consistent with its protein's role in erythrocyte invasion.\",\n      \"method\": \"Real-time quantitative PCR of synchronized P. falciparum parasites\",\n      \"journal\": \"Zhongguo ji sheng chong xue yu ji sheng chong bing za zhi\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single transcriptional profiling method, no protein-level mechanistic follow-up in this paper\",\n      \"pmids\": [\"19852359\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"PyP140/RON4 in P. yoelii localizes to the apical end of merozoites (rhoptries or micronemes) and forms a complex with AMA1; however, the conserved cysteine-rich domain, when expressed recombinantly, failed to elicit growth-inhibitory antibodies in mice, indicating this domain alone is not a protective immunogen.\",\n      \"method\": \"Monoclonal antibody screening of cDNA expression library; IFA localization; immunoprecipitation with AMA1; recombinant protein immunization and challenge in BALB/c mice\",\n      \"journal\": \"Infection and immunity\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — direct immunoprecipitation demonstrating AMA1 association; in vivo immunization challenge provides functional (negative) readout; single lab\",\n      \"pmids\": [\"18710865\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium yoelii\", \"strain\": \"YM\"}]\n    }\n  ],\n  \"current_model\": \"PfRON4 (PF3D7_1116000) is a rhoptry neck protein that is secreted during invasion and assembles with PfRON2 and PfRON5 into a stable complex; cryo-EM of this endogenous complex reveals a 1:1:1:1 sailboat-shaped assembly with PfAMA1 in which PfRON2/4/5 form a basic intracellular platform that electrostatically engages and remodels the red blood cell membrane, while on the host-cell exterior PfAMA1 contacts the RBC membrane to stabilize the moving junction; PfRON4 also participates in a second RON complex (with RON2/3) and in the SURGE complex (with SURFIN4.2 and GLURP); in sporozoites PfRON4 is present throughout the rhoptry, forms a complex with RON2 and RON5, reciprocally stabilizes RON2 trafficking to rhoptries, mediates sporozoite attachment to substrates and host cells, and is required for salivary gland colonization, sinusoidal cell traversal, and hepatocyte invasion independently of AMA1.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"RON4 (PF3D7_1116000) is a rhoptry neck protein that functions as a core structural component of the moving junction, the ring-shaped adhesion interface through which apicomplexan parasites enter host cells [#1, #6]. During P. falciparum merozoite invasion of erythrocytes, RON4 is secreted from the rhoptry necks and assembles with RON2 and RON5 and the microneme protein AMA1; cryo-EM of the endogenous invasion-stalled complex resolves a 1:1:1:1 'sailboat-shaped' assembly in which the RON2/4/5 subcomplex forms a basic intracellular platform that electrostatically engages the erythrocyte membrane and drives active host-membrane remodeling, while AMA1 stabilizes the junction from the host-cell exterior [#0]. RON4-AMA1 association occurs after merozoite reorientation and actomyosin motor engagement, placing complex assembly at a defined step preceding rhoptry-content release, and RON4 marks the adhesion ring itself, distinct from a more posterior actin traction zone [#3, #6]. RON4 additionally participates in a second RON2/3/4 complex lacking AMA1 and in the rhoptry-neck SURGE complex with SURFIN4.2 and GLURP [#5, #8]. Beyond the blood stage, RON4 acts across transmission stages: in P. berghei and P. yoelii sporozoites it redistributes throughout the rhoptry, forms a RON2/RON4/RON5 complex in which RON4 and RON2 reciprocally stabilize each other's trafficking, and is required for salivary gland colonization, sinusoidal cell traversal, sporozoite attachment and gliding onset, and hepatocyte invasion independently of AMA1 [#4, #9, #10, #11, #12]. Conserved RON4 peptide regions bind erythrocytes via protease-sensitive receptors and hepatocytes via proteoglycan-type receptors and inhibit merozoite invasion, indicating direct host-cell recognition activity [#13].\",\n  \"teleology\": [\n    {\n      \"year\": 2006,\n      \"claim\": \"Establishing that RON4 physically links the rhoptry neck to the microneme protein AMA1 defined it as a candidate structural bridge of the invasion junction in P. falciparum, extending a mechanism first seen in Toxoplasma.\",\n      \"evidence\": \"Co-immunoprecipitation and immunofluorescence localization in P. falciparum merozoites\",\n      \"pmids\": [\"16835460\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct interaction interface not mapped\", \"Stoichiometry and additional partners unresolved\", \"Functional consequence of the interaction not tested\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Demonstrating that RON4 co-purifies with RON2 and AMA1 confirmed a multi-protein moving-junction complex conserved between Toxoplasma and Plasmodium, moving RON4 from a bilateral interactor to a member of a defined assembly.\",\n      \"evidence\": \"Co-immunoprecipitation in P. falciparum; in P. yoelii, PyP140/RON4 localized apically and co-immunoprecipitated with AMA1, while its recombinant cysteine-rich domain failed to elicit protective antibodies\",\n      \"pmids\": [\"18952195\", \"18710865\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Complex architecture and subunit contacts unknown\", \"Whether all subunits associate simultaneously not resolved\", \"Protective epitopes of RON4 not identified\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}, {\"species\": \"Plasmodium yoelii\", \"strain\": \"YM\"}]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Timing RON4 transcription to the mature schizont stage tied its expression to the point in the cycle when invasion machinery is assembled.\",\n      \"evidence\": \"Quantitative RT-PCR of synchronized P. falciparum cultures\",\n      \"pmids\": [\"19852359\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Transcript-only readout with no protein-level follow-up\", \"Does not address post-transcriptional regulation or timing of secretion\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Placing RON4-AMA1 complex formation after motor engagement and before rhoptry release ordered the junction assembly within the invasion sequence, and showed the AMA1 hydrophobic trough is required for the interaction.\",\n      \"evidence\": \"R1 peptide inhibition, timed invasion assays, and Co-IP competition in P. falciparum\",\n      \"pmids\": [\"20228060\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Which RON subunit contacts the AMA1 trough not resolved\", \"Kinetics of assembly not quantified\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Genetic loss-of-function established RON4 as functionally essential for both merozoite erythrocyte invasion and sporozoite hepatocyte invasion, and revealed AMA1-independence in the sporozoite context.\",\n      \"evidence\": \"Gene knockdown/knockout in P. berghei with invasion assays in erythrocytes and hepatocytes; RON3 Co-IP in P. falciparum defined a second RON2/3/4 complex distinct from the AMA1-containing junction\",\n      \"pmids\": [\"22177563\", \"21237287\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular basis of AMA1-independence in sporozoites unknown\", \"Function of the RON2/3/4 complex (Low-confidence, single Co-IP) not tested\", \"How RON4 substitutes for the AMA1 anchor unresolved\"],\n      \"attribution\": [{\"species\": \"Plasmodium berghei\", \"strain\": \"\"}, {\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Super-resolution imaging separated the RON4-marked adhesion ring from a posterior actin traction zone, refining the physical model of how the junction couples adhesion to force generation.\",\n      \"evidence\": \"Super-resolution fluorescence microscopy of invading merozoites in P. falciparum and P. berghei\",\n      \"pmids\": [\"22389687\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Molecular coupling between the RON4 ring and actin not defined\", \"Dynamics of ring constriction not measured\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}, {\"species\": \"Plasmodium berghei\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Linking RON4 rhoptry discharge to host CD81 placed a host-membrane requirement upstream of RON4 secretion during sporozoite entry into hepatocytes.\",\n      \"evidence\": \"Fluorescent RON4 reporter live imaging in P. yoelii sporozoites comparing CD81-deficient and wild-type hepatocytes\",\n      \"pmids\": [\"24798694\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism by which CD81 triggers rhoptry discharge unknown\", \"Whether RON4 directly senses CD81 not tested\"],\n      \"attribution\": [{\"species\": \"Plasmodium yoelii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Identifying RON4 within the SURGE complex broadened its interaction network at the merozoite apex beyond the canonical RON/AMA1 junction.\",\n      \"evidence\": \"IP-mass spectrometry and immunofluorescence co-localization in P. falciparum merozoites\",\n      \"pmids\": [\"30092030\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Functional role of RON4 within SURGE not directly tested\", \"Single IP-MS study from one lab without reciprocal validation\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Demonstrating a sporozoite RON2/RON4/RON5 complex with reciprocal RON2-RON4 trafficking stabilization and a role in salivary gland attachment established RON4's stage-specific complex biology and interdependence.\",\n      \"evidence\": \"Co-IP from P. berghei sporozoite extracts, stage-specific knockdown, attachment/invasion assays, and rhoptry trafficking imaging\",\n      \"pmids\": [\"32817376\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of reciprocal stabilization unknown\", \"Why RON5 traffics independently not explained\"],\n      \"attribution\": [{\"species\": \"Plasmodium berghei\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Conditional deletion and 3D EM tied RON4-containing junction integrity to normal junction morphology and to preventing host epithelial damage, showing the complex ensures efficient and non-destructive entry across transmission stages.\",\n      \"evidence\": \"DiCre conditional deletion in P. berghei with salivary gland colonization, hepatocyte invasion assays, and 3D electron microscopy of entry junctions\",\n      \"pmids\": [\"35731833\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular cause of aberrant junction morphology not resolved\", \"Whether epithelial damage is a direct or downstream consequence unclear\"],\n      \"attribution\": [{\"species\": \"Plasmodium berghei\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Dissecting sequential sporozoite functions and identifying host-binding peptide regions showed that secreted RON4 mediates adhesion, gliding onset, cell traversal, and invasion via defined receptor interactions.\",\n      \"evidence\": \"Stage-specific knockdown with in vivo and in vitro infection, adhesion, and motility assays in P. berghei; RON4 conserved-peptide (residues 800-819, 860-879) binding to erythrocyte protease-sensitive and hepatocyte proteoglycan receptors with SPR and invasion inhibition in P. falciparum\",\n      \"pmids\": [\"37272704\", \"37030083\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Identity of the host receptor proteins not determined\", \"How a rhoptry-neck protein mediates surface adhesion before discharge unresolved\", \"Structural basis of peptide-receptor binding unknown\"],\n      \"attribution\": [{\"species\": \"Plasmodium berghei\", \"strain\": \"\"}, {\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"The cryo-EM structure of the endogenous moving junction defined RON4 as part of a basic RON2/4/5 platform that electrostatically engages and actively remodels the host membrane, elevating the complex from a passive anchor to an active membrane-remodeling machine.\",\n      \"evidence\": \"Cryo-EM of the endogenous invasion-stalled moving-junction complex purified from P. falciparum with structural analysis of transmembrane anchoring and membrane-interaction surfaces\",\n      \"pmids\": [\"42379167\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"RON4-specific contribution to the seven amphipathic helices not isolated\", \"Dynamics of membrane remodeling not captured\", \"Conformational changes during junction progression not resolved\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The molecular mechanism by which RON4 discriminates and engages host receptors, and its individual contribution to membrane remodeling versus its RON2/RON5 partners, remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Host receptor proteins bound by RON4 peptides not identified\", \"RON4-specific vs. complex-level membrane-remodeling function not separated\", \"How the same protein serves AMA1-dependent (merozoite) and AMA1-independent (sporozoite) invasion is unexplained\"],\n      \"attribution\": []\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0005515\", \"supporting_discovery_ids\": [1, 2, 5, 8, 10, 15]},\n      {\"term_id\": \"GO:0046872\", \"supporting_discovery_ids\": [13]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0070005\", \"supporting_discovery_ids\": [1, 8]},\n      {\"term_id\": \"GO:0020008\", \"supporting_discovery_ids\": [9]},\n      {\"term_id\": \"GO:0020009\", \"supporting_discovery_ids\": [6]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0044409\", \"supporting_discovery_ids\": [0, 3, 4, 6, 11, 12, 13]},\n      {\"term_id\": \"GO:0007155\", \"supporting_discovery_ids\": [10, 12, 13]},\n      {\"term_id\": \"GO:0016477\", \"supporting_discovery_ids\": [12]}\n    ],\n    \"complexes\": [\n      \"Moving junction complex (RON2/RON4/RON5/AMA1)\",\n      \"RON2/RON3/RON4 complex\",\n      \"SURGE complex (RON4/SURFIN4.2/GLURP)\",\n      \"Sporozoite RON2/RON4/RON5 complex\"\n    ],\n    \"partners\": [\n      \"AMA1\",\n      \"RON2\",\n      \"RON5\",\n      \"RON3\",\n      \"SURFIN4.2\",\n      \"GLURP\"\n    ],\n    \"other_free_text\": [\n      \"Transcription peaks at mature schizont stage (36-40 h post-invasion) in P. falciparum [#14]\",\n      \"Secreted from rhoptry necks; discharge depends on host CD81 in P. yoelii sporozoites [#7]\",\n      \"RON4 and RON2 reciprocally stabilize each other's trafficking to rhoptries; RON5 traffics independently in P. berghei sporozoites [#10]\",\n      \"Conserved peptide regions (residues 800-819, 860-879) bind erythrocyte protease-sensitive receptors and hepatocyte proteoglycan-type receptors [#13]\",\n      \"RON2/4/5 platform wedges seven amphipathic helices into the RBC bilayer and electrostatically remodels host membrane [#0]\",\n      \"Functions in sporozoite salivary gland colonization, sinusoidal cell traversal, gliding onset, and hepatocyte invasion, AMA1-independently [#4, #11, #12]\"\n    ]\n  }\n}","audit_flag":null,"strains":[{"strain":"Pf3D7","gene_id":"PF3D7_1116000","name":null,"product":"rhoptry neck protein 4","uniprot_acc":null,"chromosome":null,"start_pos":null},{"strain":"PbANKA","gene_id":"PBANKA_0932000","name":null,"product":"rhoptry neck protein 4","uniprot_acc":null,"chromosome":null,"start_pos":null},{"strain":"PkH","gene_id":"PKNH_0913700","name":null,"product":"rhoptry neck protein 4, putative","uniprot_acc":null,"chromosome":null,"start_pos":null}],"gene_symbol":"RON4","evaluation":null}