{"gene":"PF3D7_1452000","run_date":"2026-09-08T14:19:07","timeline":{"discoveries":[{"year":2008,"finding":"P. falciparum RON2 (PfRON2) localizes to the neck portion of the rhoptry in merozoites, is transcribed at peak levels at the mature schizont stage, and forms a complex with PfRON4 and PfAMA1 as demonstrated by co-immunoprecipitation, establishing conservation of the moving junction complex between T. gondii and P. falciparum. Co-immunoprecipitation studies also showed that PfRON2 is NOT a component of the RhopH complex.","method":"Co-immunoprecipitation, immunofluorescence microscopy, transcriptional analysis","journal":"Parasitology international","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP with multiple partners, single lab, immunofluorescence localization, consistent with later work","pmids":["18952195"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2010,"finding":"The R1 invasion-inhibitory peptide binds the PfAMA1 hydrophobic trough and prevents PfAMA1 interaction with the PfRON complex (including RON2), placing the AMA1-RON2 interaction after merozoite reorientation and actomyosin motor engagement during the invasion sequence.","method":"Peptide-binding assays, invasion inhibition assays, epistasis/temporal ordering by sequential blocking","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional inhibition assay with mechanistic placement in invasion sequence, single lab, multiple methods","pmids":["20228060"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2011,"finding":"P. falciparum RON2 is inserted as an integral membrane protein in the host cell membrane during invasion. Using native and recombinant protein interaction assays, the extracellular region of RON2 that binds AMA1 was defined, and invasion inhibition assays confirmed that the RON2-AMA1 interaction is required for P. falciparum merozoite entry into erythrocytes.","method":"Integral membrane protein insertion assay, native and recombinant protein interaction assays, invasion inhibition assays","journal":"PLoS pathogens","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — multiple orthogonal methods (membrane insertion, interaction assays, functional inhibition), replicated across species","pmids":["21347343"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2011,"finding":"The RON2 peptide binding site on AMA1 is its hydrophobic pocket. Two conserved, disulfide-linked cysteines in the RON2 peptide are critical residues required for binding to the AMA1 hydrophobic pocket. RON2-AMA1 binding triggers junction formation and commits P. falciparum merozoites to RBC invasion. The RON2 peptide blocked junction formation but, unlike AMA1-specific antibodies targeting the pocket, did not block parasitophorous vacuole formation, indicating junction formation and vacuole formation are molecularly distinct steps.","method":"Antibody blocking assays, AMA1 pocket mutants, RON2 peptide competition assays, live microscopy of junction and vacuole formation","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — site-directed mutagenesis of both binding partners, multiple functional assays, mechanistically distinct steps demonstrated","pmids":["21788485"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2011,"finding":"The C-terminal cysteine-rich domain of PfRON2 binds host erythrocytes (as shown by COS-7 surface rosetting assay), and both the C-terminal and central cysteine-rich domains of PfRON2 interact with PfAMA1; this binding can be inhibited by mAb 4G2 targeting the AMA1 hydrophobic groove, indicating the hydrophobic groove of PfAMA1 is the binding site for PfRON2.","method":"COS-7 surface expression rosetting assay, binding inhibition with monoclonal antibody","journal":"Parasitology research","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — domain mapping via cell-surface expression and rosetting, antibody competition, single lab, two methods","pmids":["22033736"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2011,"finding":"PfRON2 also forms a complex with PfRON3 and PfRON4 (without PfAMA1), as shown by co-immunoprecipitation, constituting a novel RON complex (PfRON2/3/4) distinct from the moving junction complex (PfRON2/4/5/AMA1).","method":"Co-immunoprecipitation","journal":"Parasitology international","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single Co-IP experiment, single lab, single method","pmids":["21237287"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2012,"finding":"Crystal structure of PfAMA1 in complex with a peptide derived from the extracellular region of PfRON2 was determined. The receptor-binding site of PfAMA1 comprises the hydrophobic groove and a region exposed by displacement of the flexible Domain II loop. Mutations of key contact residues in PfRON2 and PfAMA1 abrogate binding between the recombinant proteins. The PfRON2 peptide inhibits P. falciparum erythrocyte invasion, and this inhibitory potency is not affected by AMA1 polymorphisms. The R1 inhibitory peptide mimics the PfRON2 peptide structurally in binding to PfAMA1.","method":"X-ray crystallography, site-directed mutagenesis, binding assays, invasion inhibition assay","journal":"PLoS pathogens","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structure plus mutagenesis plus functional invasion inhibition assay in single rigorous study","pmids":["22737069"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2012,"finding":"In P. falciparum merozoites, RON2 (Rhoptry Neck Protein 2) is released early during invasion, following the junction, as determined by high-definition imaging of endogenously tagged proteins, supporting the model that RON2 is among the first rhoptry neck proteins secreted during invasion.","method":"Endogenous gene tagging, high-definition live and fixed fluorescence imaging","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — endogenous tagging with direct imaging showing secretion timing, single lab","pmids":["23049965"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2013,"finding":"A small molecule identified by high-throughput screening inhibits P. falciparum merozoite invasion by binding to AMA1 and blocking formation of the AMA1-RON2 complex; electron microscopy confirmed this inhibitor prevents tight junction formation, directly linking AMA1-RON2 complex formation to junction formation during invasion.","method":"High-throughput compound screening, binding assay, electron microscopy, invasion inhibition assay","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — multiple orthogonal methods (biochemical binding, EM junction morphology, functional invasion assay), mechanism directly demonstrated","pmids":["23907321"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2015,"finding":"Live cell imaging with systematic blocking of receptor-ligand interactions established the temporal sequence of invasion: the AMA1-RON2 interaction mediates tight junction formation, which acts as an anchor point for parasite internalization, occurring after the PfRh5-basigin binding step.","method":"Live cell imaging, genetic deletion, enzymatic receptor cleavage, inhibitory antibodies and peptides","journal":"PLoS pathogens","confidence":"High","confidence_rationale":"Tier 2 / Strong — systematic epistasis using multiple orthogonal blocking methods with live imaging, replicated across multiple invasion steps","pmids":["25723550"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2016,"finding":"The Domain II (DII) loop of PfAMA1 kinetically stabilizes the PfAMA1-RON2 complex by lengthening the complex half-life 18-fold (from ~48 s to ~900 s at 25°C) by slowing the dissociation rate, as determined by fluorescence anisotropy kinetic and thermodynamic measurements comparing wild-type PfAMA1 and a ΔDII-loop engineered construct.","method":"Fluorescence anisotropy kinetics, isothermal titration calorimetry, engineered deletion mutant","journal":"PloS one","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro reconstitution with mutagenesis (deletion mutant), quantitative kinetics via two orthogonal methods, single lab","pmids":["26731670"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2009,"finding":"In P. berghei, RON2 (PBRON2) localizes to the rhoptries in merozoites and is also expressed in sporozoites with the same timing and apical rhoptry location as the known rhoptry protein RAP2/3, establishing RON2 rhoptry localization across both invasion stages.","method":"GFP/MYC epitope tagging, fluorescence microscopy, cross-lifecycle expression analysis","journal":"Molecular and biochemical parasitology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct localization by endogenous fluorescent tagging across multiple life cycle stages, single lab","pmids":["19428669"],"is_preprint":false,"attribution":[{"species":"Plasmodium berghei","strain":""}]},{"year":2014,"finding":"In P. yoelii sporozoites, RON2 and RON4 are lost following rhoptry discharge during entry into host cells (analogous to merozoite entry), and rhoptry discharge of RON2/RON4 in sporozoites requires the host membrane protein CD81, as sporozoites failed to discharge rhoptries in CD81-negative conditions.","method":"Transgenic P. yoelii expressing fluorescent RON2/RON4/RAP2-3, fluorescence microscopy, CD81-dependent entry assay","journal":"Cellular microbiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct imaging of RON2 discharge in live transgenic parasites with genetic/host factor dependency established, single lab","pmids":["24798694"],"is_preprint":false,"attribution":[{"species":"Plasmodium yoelii","strain":""}]},{"year":2018,"finding":"In P. berghei, RON2 is localized to rhoptries in sporozoites. Sporozoite stage-specific knockdown of ron2 (by promoter swapping to restrict transcription to intraerythrocytic stages) severely impaired sporozoite invasion of mosquito salivary glands by decreasing attachment capacity, and also reduced infectivity to hepatocytes, demonstrating a functional role for RON2 in sporozoite invasion distinct from its role in merozoite invasion.","method":"Promoter swapping strategy for stage-specific knockdown, salivary gland invasion assay, hepatocyte infection assay, immunofluorescence","journal":"Cellular microbiology","confidence":"High","confidence_rationale":"Tier 2 / Strong — stage-specific genetic knockdown with specific invasion phenotype quantified across two host cell types, multiple functional readouts","pmids":["30307699"],"is_preprint":false,"attribution":[{"species":"Plasmodium berghei","strain":""}]},{"year":2019,"finding":"In P. berghei sporozoites, RON2 localizes to rhoptries (confirmed by immuno-electron microscopy). Unlike merozoites where RON2 and RON4 are neck-restricted, most rhoptry neck proteins including RON2 localize throughout the rhoptries in sporozoites, indicating stage-specific differences in subcompartmentalization.","method":"Immuno-electron microscopy, immunofluorescence assay","journal":"Frontiers in cellular and infection microbiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — immuno-EM with direct localization, single lab, single species","pmids":["31552198"],"is_preprint":false,"attribution":[{"species":"Plasmodium berghei","strain":""}]},{"year":2020,"finding":"In P. berghei sporozoites, RON2, RON4, and RON5 form a complex (as demonstrated by co-immunoprecipitation from oocyst-derived sporozoite extracts). Stage-specific knockdown revealed that RON2 and RON4 reciprocally affect each other's trafficking to rhoptries in developing sporozoites, while RON5 is independently transported. RON4 and RON5 knockdown reduced sporozoite attachment and salivary gland invasion.","method":"Co-immunoprecipitation from sporozoite extracts, sporozoite stage-specific gene knockdown, salivary gland invasion assay, fluorescence microscopy","journal":"mSphere","confidence":"High","confidence_rationale":"Tier 2 / Strong — co-IP from native sporozoite extracts plus reciprocal trafficking effects shown by genetic knockdown in two partners, multiple functional readouts","pmids":["32817376"],"is_preprint":false,"attribution":[{"species":"Plasmodium berghei","strain":""}]},{"year":2022,"finding":"In P. berghei, conditional DiCre-mediated deletion of RON2 (or RON4) in sporozoites impairs 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 led to altered morphology of the entry junction, associated with epithelial cell damage, establishing that RON2 is required for forming a proper invasion junction in sporozoites.","method":"DiCre-mediated conditional gene deletion, mosquito salivary gland invasion assay, hepatocyte invasion assay, 3D electron microscopy","journal":"PLoS pathogens","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — conditional genetic KO with specific invasion phenotypes plus 3D-EM structural phenotype, multiple invasion stages, rigorous controls","pmids":["35731833"],"is_preprint":false,"attribution":[{"species":"Plasmodium berghei","strain":""}]},{"year":2021,"finding":"In P. yoelii merozoites, PyRON2 was already present on the merozoite surface immediately after egress (prior to erythrocyte encounter), and its secretion was not affected by PKAc disruption, in contrast to AMA1. This is inconsistent with the model that RON2 is injected exclusively into the erythrocyte cytosol from within the host, suggesting RON2 may be exposed on the merozoite surface before invasion.","method":"DiCre-loxP inducible knockout of PKAc, immunofluorescence microscopy for RON2 localization at egress, erythrocyte invasion assay","journal":"Parasitology international","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct imaging at defined invasion stages using inducible KO system, single lab, single species, conflicts with current model","pmids":["34390881"],"is_preprint":false,"attribution":[{"species":"Plasmodium yoelii","strain":""}]},{"year":2026,"finding":"Cryo-EM structure of the endogenous P. falciparum moving junction purified from invasion-stalled parasites revealed a 1:1:1:1 assembly of PfAMA1 with PfRON2, PfRON4, and PfRON5. PfRON2 contains two transmembrane helices that anchor the complex in the red blood cell membrane and display an extracellular handle for PfAMA1 binding. PfAMA1 directly contacts the RBC membrane. PfRON2/4/5 form a large basic platform inside the RBC that electrostatically engages the RBC membrane and embeds amphipathic helices into the bilayer, suggesting RON2 participates in host membrane remodeling during invasion.","method":"Cryo-EM structural determination of endogenous complex purified from invasion-stalled P. falciparum, computational protein design of binder","journal":"Cell","confidence":"High","confidence_rationale":"Tier 1 / Strong — near-atomic cryo-EM structure of endogenous complex with functional validation by designed inhibitor, rigorous methodology","pmids":["42379167"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2025,"finding":"Computational simulation of DII loop dynamics in the PfAMA1-PfRON2 complex identified key residues in the PfRON2 helix essential for the post-binding lock conformation. Experimental mutagenesis of these residues validated their functional importance in complex stabilization.","method":"Molecular dynamics simulation, mutagenesis with experimental binding validation","journal":"Chembiochem : a European journal of chemical biology","confidence":"Medium","confidence_rationale":"Tier 1-2 / Moderate — computation guided mutagenesis with experimental binding validation, single lab, single study","pmids":["40067319"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2019,"finding":"For P. vivax RON2, the disulfide bond between C2051 and C2063 in the cyclic form of the PvRON2 peptide is essential for interaction with PvAMA1; the linear peptide lacking this bond showed no detectable interaction by SPR or ITC, establishing that the RON2 disulfide-constrained structure is required for AMA1 binding.","method":"Surface plasmon resonance, isothermal titration calorimetry, far western blot, circular dichroism, SAXS","journal":"Malaria journal","confidence":"High","confidence_rationale":"Tier 1 / Moderate — multiple biophysical methods (SPR, ITC, CD, SAXS) with direct structural requirement demonstrated by cyclic vs linear comparison, single lab","pmids":["30683104"],"is_preprint":false,"attribution":[{"species":"Plasmodium vivax","strain":""}]},{"year":2017,"finding":"Crystal structure of the complex formed between PvAMA1 and PvRON2sp1 peptide was determined. Binding studies showed PvRON2sp1 has strong cross-reactivity with PfAMA1, but PfRON2sp1 has no detectable interaction with PvAMA1; the species asymmetry was largely attributable to PvRON2-Thr2055 versus PfRON2-Arg2041.","method":"X-ray crystallography, surface plasmon resonance binding assays","journal":"PloS one","confidence":"High","confidence_rationale":"Tier 1 / Moderate — crystal structures plus quantitative SPR binding data in single study, specific residue identified for species specificity","pmids":["28817634"],"is_preprint":false,"attribution":[{"species":"Plasmodium vivax","strain":""},{"species":"Plasmodium falciparum","strain":""}]},{"year":2023,"finding":"Specific residues in the β-hairpin loop of RON2 and specific residues in AMA1 Loop1E determine species-specific binding between AMA1 and RON2 in P. falciparum and P. vivax. Mutation of specific amino acids in AMA1 Loop1E in P. falciparum ablated RON2 binding without impacting erythrocyte invasion, demonstrating that the AMA1-RON2-loop interaction is NOT essential for invasion and that additional AMA1 interactions are involved.","method":"Site-directed mutagenesis of AMA1 and RON2, erythrocyte invasion assay, binding assays","journal":"Cellular and molecular life sciences : CMLS","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — mutagenesis of both binding partners with quantitative functional invasion readout, unexpected negative finding for essentiality of this interaction","pmids":["36847896"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""},{"species":"Plasmodium vivax","strain":""}]}],"current_model":"P. falciparum RON2 (PF3D7_1452000) is a rhoptry neck protein that, during merozoite invasion, is discharged and inserted as an integral membrane protein into the host erythrocyte membrane via two transmembrane helices; its extracellular loop binds the hydrophobic groove of the parasite surface protein AMA1 in a disulfide-dependent manner to form a 1:1:1:1 moving junction complex with RON4 and RON5, thereby anchoring the parasite to the erythrocyte and driving internalization, while the RON2/4/5 platform inside the RBC also participates in host membrane remodeling; RON2 similarly localizes to rhoptries in sporozoites, where it is required for invasion of both mosquito salivary glands and mammalian hepatocytes, and RON2 and RON4 reciprocally stabilize each other's trafficking to rhoptries."},"narrative":{"mechanistic_narrative":"RON2 (PF3D7_1452000) is a rhoptry neck protein that serves as the parasite-supplied membrane anchor of the moving junction, the tight-junction structure through which apicomplexan parasites invade host cells [PMID:18952195, PMID:21347343]. In P. falciparum merozoites, RON2 localizes to the neck of the rhoptry, peaks in transcription at the mature schizont stage, and is discharged early during invasion, after which it is inserted as an integral membrane protein into the host erythrocyte membrane [PMID:18952195, PMID:21347343, PMID:23049965]. Its extracellular region binds the hydrophobic groove of the parasite surface protein AMA1 in a manner that requires two conserved, disulfide-linked cysteines in the RON2 peptide, and this AMA1-RON2 engagement triggers tight-junction formation that anchors the parasite and commits the merozoite to invasion [PMID:21347343, PMID:21788485, PMID:22737069]. Junction formation via AMA1-RON2 is a molecularly distinct step from parasitophorous vacuole formation and occurs downstream of the PfRh5-basigin binding step in the invasion sequence [PMID:21788485, PMID:25723550]. A cryo-EM structure of the endogenous complex shows a 1:1:1:1 assembly of AMA1 with RON2, RON4, and RON5, in which two RON2 transmembrane helices anchor the complex in the erythrocyte membrane and present an extracellular handle for AMA1 binding, while the RON2/4/5 platform inside the red cell electrostatically engages and embeds into the membrane bilayer, implicating RON2 in host membrane remodeling [PMID:42379167]. Beyond its erythrocytic role, RON2 also localizes to rhoptries in sporozoites and is required for invasion of both mosquito salivary glands and mammalian hepatocytes, where loss of a functional AMA1-RON complex alters the entry junction morphology [PMID:30307699, PMID:35731833]. Notably, mutations in the AMA1 Loop1E that ablate RON2-loop binding do not impair erythrocyte invasion, indicating additional AMA1 interactions contribute and that the isolated AMA1-RON2 loop contact is not strictly essential [PMID:36847896].","teleology":[{"year":2008,"claim":"Establishing that P. falciparum possesses a moving-junction complex was needed to test whether the apicomplexan invasion machinery is conserved beyond T. gondii; localizing RON2 to the rhoptry neck and showing it complexes with RON4 and AMA1 defined RON2 as a core junction component and excluded it from the RhopH complex.","evidence":"Co-immunoprecipitation, immunofluorescence, and transcriptional analysis in P. falciparum merozoites","pmids":["18952195"],"confidence":"Medium","gaps":["Interaction shown by Co-IP without stoichiometry or direct binding interface","Functional requirement of RON2 for invasion not yet demonstrated"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2011,"claim":"Whether RON2 acts on the parasite or host side of the junction and whether its AMA1 contact is functionally required were unresolved; showing RON2 inserts as an integral host-membrane protein and mapping its AMA1-binding extracellular region with invasion-blocking assays established RON2 as the host-membrane-anchored receptor for AMA1 driving entry.","evidence":"Membrane insertion assay, native/recombinant interaction assays, and invasion inhibition in P. falciparum","pmids":["21347343","22033736"],"confidence":"High","gaps":["Molecular topology of the two transmembrane segments not yet defined","Nature of the host-membrane insertion mechanism unresolved"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2011,"claim":"The chemistry of the RON2-AMA1 interface and its precise role in the invasion sequence were unknown; identifying two disulfide-linked cysteines as critical for binding to the AMA1 hydrophobic pocket and showing the RON2 peptide blocks junction but not vacuole formation established that this interaction triggers a discrete commitment step.","evidence":"AMA1 pocket mutants, RON2 peptide competition, antibody blocking, and live imaging of junction versus vacuole formation in P. falciparum","pmids":["21788485"],"confidence":"High","gaps":["Structural basis of the disulfide-constrained peptide binding not yet resolved at atomic level","Relationship between RON2 peptide and full-length RON2 behavior not addressed"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2012,"claim":"Atomic-resolution understanding of how RON2 engages AMA1 and whether the interface is a drug target were needed; crystallography of the AMA1-RON2 peptide complex defined the hydrophobic groove plus Domain-II-loop-displaced site and showed the RON2 peptide inhibits invasion irrespective of AMA1 polymorphism.","evidence":"X-ray crystallography, site-directed mutagenesis, binding and invasion inhibition assays in P. falciparum","pmids":["22737069"],"confidence":"High","gaps":["Peptide-only structure does not capture the full-length transmembrane-anchored complex","Kinetics of complex formation and stabilization not addressed"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2012,"claim":"The timing of RON2 secretion relative to junction formation was uncertain; high-definition imaging of endogenously tagged RON2 showed it is released early, among the first rhoptry neck proteins secreted during invasion.","evidence":"Endogenous gene tagging with live and fixed high-definition fluorescence imaging in P. falciparum","pmids":["23049965"],"confidence":"Medium","gaps":["Mechanism of rhoptry discharge triggering not defined","Whether secretion timing differs across species not addressed"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2015,"claim":"The position of the AMA1-RON2 junction within the ordered invasion cascade was unresolved; systematic blocking with live imaging placed AMA1-RON2-mediated tight-junction formation downstream of PfRh5-basigin binding, defining it as the anchoring step for internalization.","evidence":"Live cell imaging with genetic deletion, receptor cleavage, and inhibitory antibodies/peptides in P. falciparum","pmids":["25723550","23907321"],"confidence":"High","gaps":["Molecular coupling between junction and the actomyosin motor not detailed","How the junction physically anchors internalization not structurally defined"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2016,"claim":"Why the AMA1 Domain II loop matters for a productive junction was unclear; kinetic measurements showed the DII loop stabilizes the AMA1-RON2 complex 18-fold by slowing dissociation, revealing a post-binding locking mechanism.","evidence":"Fluorescence anisotropy kinetics, ITC, and a DII-loop deletion mutant in P. falciparum","pmids":["26731670"],"confidence":"High","gaps":["Structural conformation of the locked state not directly visualized","Physiological consequence of altered half-life on invasion efficiency not quantified"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2019,"claim":"Whether the disulfide-constrained RON2 conformation is a general binding requirement across Plasmodium species was untested; comparison of cyclic versus linear PvRON2 peptides showed the C2051-C2063 disulfide is essential for PvAMA1 binding, and cross-species structural work identified single residues driving species-specific recognition.","evidence":"SPR, ITC, CD, SAXS with cyclic/linear peptide comparison in P. vivax; crystallography and SPR across P. vivax and P. falciparum","pmids":["30683104","28817634"],"confidence":"High","gaps":["Species-specificity determinants tested largely with peptides, not full-length proteins","Consequences for cross-species invasion in vivo not addressed"],"attribution":[{"species":"Plasmodium vivax","strain":""},{"species":"Plasmodium falciparum","strain":""}]},{"year":2023,"claim":"Whether the AMA1-RON2 loop contact is strictly essential for invasion was assumed but untested; mutating AMA1 Loop1E to ablate RON2 binding without impairing erythrocyte invasion showed the isolated loop interaction is dispensable and that additional AMA1 contacts contribute.","evidence":"Site-directed mutagenesis of AMA1 and RON2 with erythrocyte invasion and binding assays in P. falciparum and P. vivax","pmids":["36847896"],"confidence":"High","gaps":["Identity of the compensating additional AMA1-RON2 contacts not defined","Whether redundancy applies to sporozoite invasion not tested"],"attribution":[{"species":"Plasmodium falciparum","strain":""},{"species":"Plasmodium vivax","strain":""}]},{"year":2018,"claim":"Whether RON2 functions beyond the blood stage was unknown; in P. berghei, sporozoite-stage-specific ron2 knockdown impaired salivary gland invasion by reducing attachment and reduced hepatocyte infectivity, establishing a distinct RON2 role in sporozoite invasion.","evidence":"Promoter-swap stage-specific knockdown with salivary gland and hepatocyte invasion assays in P. berghei","pmids":["30307699"],"confidence":"High","gaps":["Whether sporozoite RON2 engages AMA1 in the same way as merozoite RON2 not established","Direct binding partners at the sporozoite junction not defined"],"attribution":[{"species":"Plasmodium berghei","strain":""}]},{"year":2020,"claim":"How the sporozoite RON complex is assembled and trafficked was unknown; Co-IP from sporozoite extracts plus stage-specific knockdown showed RON2, RON4, and RON5 form a complex and that RON2 and RON4 reciprocally depend on each other for rhoptry trafficking, whereas RON5 is transported independently.","evidence":"Co-IP from oocyst-derived sporozoite extracts and stage-specific knockdown with invasion assays in P. berghei","pmids":["32817376"],"confidence":"High","gaps":["Molecular basis of the reciprocal RON2/RON4 trafficking dependency not defined","Whether the same interdependence operates in merozoites not tested"],"attribution":[{"species":"Plasmodium berghei","strain":""}]},{"year":2022,"claim":"Whether RON2 is genuinely required to build a functional entry junction in sporozoites, versus merely present, was unresolved; conditional deletion of RON2 impaired salivary gland colonization and hepatocyte invasion without affecting transcellular migration, and 3D-EM revealed an altered entry junction morphology.","evidence":"DiCre conditional deletion with invasion assays and 3D electron microscopy in P. berghei","pmids":["35731833"],"confidence":"High","gaps":["Structural detail of the sporozoite junction at molecular resolution not defined","Host receptor on salivary gland/hepatocyte engaged by the sporozoite RON complex not identified"],"attribution":[{"species":"Plasmodium berghei","strain":""}]},{"year":2026,"claim":"The architecture of the full endogenous moving junction and RON2's membrane role were unresolved; cryo-EM of the invasion-stalled complex revealed a 1:1:1:1 AMA1-RON2-RON4-RON5 assembly with two RON2 transmembrane helices anchoring the complex and a RON2/4/5 platform embedding into the RBC membrane, implicating RON2 in host membrane remodeling.","evidence":"Cryo-EM of endogenous complex purified from invasion-stalled P. falciparum with a computationally designed binder","pmids":["42379167"],"confidence":"High","gaps":["Dynamics of membrane insertion and remodeling not directly captured","Mechanistic link between the basic platform and internalization force not defined"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":null,"claim":"It remains unresolved whether RON2 is delivered exclusively into the host membrane from within the erythrocyte or is also exposed on the merozoite surface before invasion, and how these competing observations reconcile with the moving-junction model.","evidence":"P. yoelii imaging showed RON2 present on the merozoite surface immediately after egress and secreted independently of PKAc, contrasting with AMA1","pmids":[],"confidence":"Medium","gaps":["Direct visualization of RON2 topology during live invasion lacking","Species differences (P. yoelii versus P. falciparum) may confound interpretation","Timing of surface exposure relative to host-membrane insertion unresolved"],"attribution":[{"species":"Plasmodium yoelii","strain":""}]}],"mechanism_profile":{"molecular_activity":[],"localization":[],"pathway":[],"complexes":["Moving junction complex: AMA1-RON2-RON4-RON5 (1:1:1:1) [#0, #18]","PfRON2/RON3/RON4 complex distinct from the moving junction [#5]","Sporozoite RON2/RON4/RON5 complex [#15]"],"partners":["AMA1 (BINDS RON2 EXTRACELLULAR REGION VIA HYDROPHOBIC GROOVE) [#2, #3, #4, #6]","RON4 (COMPLEX PARTNER; RECIPROCAL TRAFFICKING DEPENDENCY IN SPOROZOITES) [#0, #15]","RON5 (MOVING JUNCTION AND SPOROZOITE COMPLEX PARTNER) [#15, #18]","RON3 (PFRON2/3/4 COMPLEX) [#5]","HOST ERYTHROCYTE MEMBRANE (INTEGRAL INSERTION; C-TERMINAL CYSTEINE-RICH DOMAIN BINDS ERYTHROCYTES) [#2, #4, #18]"],"other_free_text":["Two conserved disulfide-linked cysteines in the RON2 peptide are critical for AMA1 hydrophobic-pocket binding [#3]; disulfide-constrained cyclic conformation required for AMA1 binding in P. vivax [#20].","AMA1 Domain II loop kinetically stabilizes the AMA1-RON2 complex ~18-fold by slowing dissociation [#10]; specific RON2 helix residues mediate a post-binding lock conformation [#19].","AMA1 Loop1E mutations that ablate RON2-loop binding do not impair erythrocyte invasion, indicating the isolated loop contact is not essential and additional AMA1 interactions contribute [#22].","Two RON2 transmembrane helices anchor the complex in the RBC membrane; the intracellular RON2/4/5 platform embeds amphipathic helices, implicating RON2 in host membrane remodeling [#18].","Sporozoite rhoptry discharge of RON2/RON4 requires host CD81 in P. yoelii [#12]; sporozoite RON2 distributes throughout the rhoptry rather than being neck-restricted as in merozoites [#14].","Species-specific AMA1-RON2 recognition maps to single residues (e.g. PvRON2-Thr2055 vs PfRON2-Arg2041) [#21].","In P. yoelii, RON2 was detected on the merozoite surface after egress and secreted independently of PKAc, conflicting with exclusive host-cytosol injection [#17]."]}},"prefetch_data":{},"corpus_meta":[{"pmid":"21347343","id":"PMC_21347343","title":"The RON2-AMA1 interaction is a critical step in moving junction-dependent invasion by apicomplexan parasites.","date":"2011","source":"PLoS 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PfRon2 Does Not Improve the In Vitro Efficacy.","date":"2017","source":"Frontiers in immunology","url":"https://pubmed.ncbi.nlm.nih.gov/28702028","citation_count":4,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["PfRON2","PyRON2"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"22321319","id":"PMC_22321319","title":"Positive diversifying selection on Plasmodium vivax RON2 protein.","date":"2012","source":"Parasitology","url":"https://pubmed.ncbi.nlm.nih.gov/22321319","citation_count":3,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["RON2","rhoptry neck protein 2","PvRON2"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"39324028","id":"PMC_39324028","title":"Conformational variability in the D2 loop of Plasmodium Apical Membrane antigen 1.","date":"2024","source":"Journal of structural biology: X","url":"https://pubmed.ncbi.nlm.nih.gov/39324028","citation_count":2,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["RON2"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"36504817","id":"PMC_36504817","title":"Vesicular stomatitis virus-based vaccine targeting plasmodium blood-stage antigens elicits immune response and protects against malaria with protein booster strategy.","date":"2022","source":"Frontiers in microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/36504817","citation_count":2,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["RON2","rhoptry neck protein 2"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"34390881","id":"PMC_34390881","title":"cAMP-dependent protein kinase regulates secretion of apical membrane antigen 1 (AMA1) in Plasmodium yoelii.","date":"2021","source":"Parasitology 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biology","url":"https://pubmed.ncbi.nlm.nih.gov/38370683","citation_count":0,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["RON2"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"37131813","id":"PMC_37131813","title":"Structure guided mimicry of an essential P. falciparum receptor-ligand complex enhances cross neutralizing antibodies.","date":"2023","source":"Research square","url":"https://pubmed.ncbi.nlm.nih.gov/37131813","citation_count":0,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["RON2","rhoptry neck protein 2"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"40198064","id":"PMC_40198064","title":"Chemical Protein Engineering: Backbone Cyclization Rescues Folding of a 183-Residue Truncated Domain of Malaria Parasite Protein PfAMA1.","date":"2025","source":"Chemistry (Weinheim an der Bergstrasse, Germany)","url":"https://pubmed.ncbi.nlm.nih.gov/40198064","citation_count":0,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["rhoptry neck protein 2","PfRON2"],"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":["PfRON2"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"40062812","id":"PMC_40062812","title":"Chemically Engineered Peptide Efficiently Blocks Malaria Parasite Entry into Red Blood Cells.","date":"2025","source":"Biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/40062812","citation_count":0,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["PfRON2"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":35519,"output_tokens":6355,"usd":0.100941,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":13559,"output_tokens":6196,"usd":0.111348,"stage2_stop_reason":"end_turn"},"total_usd":0.212289,"stage1_batch_id":"msgbatch_011BPjN2BL33F8cJXD1r7V7T","stage2_batch_id":"msgbatch_01Qwg6vP7qxkpL6Gsc7tajsb","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2008,\n      \"finding\": \"P. falciparum RON2 (PfRON2) localizes to the neck portion of the rhoptry in merozoites, is transcribed at peak levels at the mature schizont stage, and forms a complex with PfRON4 and PfAMA1 as demonstrated by co-immunoprecipitation, establishing conservation of the moving junction complex between T. gondii and P. falciparum. Co-immunoprecipitation studies also showed that PfRON2 is NOT a component of the RhopH complex.\",\n      \"method\": \"Co-immunoprecipitation, immunofluorescence microscopy, transcriptional analysis\",\n      \"journal\": \"Parasitology international\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP with multiple partners, single lab, immunofluorescence localization, consistent with later work\",\n      \"pmids\": [\"18952195\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"The R1 invasion-inhibitory peptide binds the PfAMA1 hydrophobic trough and prevents PfAMA1 interaction with the PfRON complex (including RON2), placing the AMA1-RON2 interaction after merozoite reorientation and actomyosin motor engagement during the invasion sequence.\",\n      \"method\": \"Peptide-binding assays, invasion inhibition assays, epistasis/temporal ordering by sequential blocking\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional inhibition assay with mechanistic placement in invasion sequence, single lab, multiple methods\",\n      \"pmids\": [\"20228060\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"P. falciparum RON2 is inserted as an integral membrane protein in the host cell membrane during invasion. Using native and recombinant protein interaction assays, the extracellular region of RON2 that binds AMA1 was defined, and invasion inhibition assays confirmed that the RON2-AMA1 interaction is required for P. falciparum merozoite entry into erythrocytes.\",\n      \"method\": \"Integral membrane protein insertion assay, native and recombinant protein interaction assays, invasion inhibition assays\",\n      \"journal\": \"PLoS pathogens\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — multiple orthogonal methods (membrane insertion, interaction assays, functional inhibition), replicated across species\",\n      \"pmids\": [\"21347343\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"The RON2 peptide binding site on AMA1 is its hydrophobic pocket. Two conserved, disulfide-linked cysteines in the RON2 peptide are critical residues required for binding to the AMA1 hydrophobic pocket. RON2-AMA1 binding triggers junction formation and commits P. falciparum merozoites to RBC invasion. The RON2 peptide blocked junction formation but, unlike AMA1-specific antibodies targeting the pocket, did not block parasitophorous vacuole formation, indicating junction formation and vacuole formation are molecularly distinct steps.\",\n      \"method\": \"Antibody blocking assays, AMA1 pocket mutants, RON2 peptide competition assays, live microscopy of junction and vacuole formation\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — site-directed mutagenesis of both binding partners, multiple functional assays, mechanistically distinct steps demonstrated\",\n      \"pmids\": [\"21788485\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"The C-terminal cysteine-rich domain of PfRON2 binds host erythrocytes (as shown by COS-7 surface rosetting assay), and both the C-terminal and central cysteine-rich domains of PfRON2 interact with PfAMA1; this binding can be inhibited by mAb 4G2 targeting the AMA1 hydrophobic groove, indicating the hydrophobic groove of PfAMA1 is the binding site for PfRON2.\",\n      \"method\": \"COS-7 surface expression rosetting assay, binding inhibition with monoclonal antibody\",\n      \"journal\": \"Parasitology research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — domain mapping via cell-surface expression and rosetting, antibody competition, single lab, two methods\",\n      \"pmids\": [\"22033736\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"PfRON2 also forms a complex with PfRON3 and PfRON4 (without PfAMA1), as shown by co-immunoprecipitation, constituting a novel RON complex (PfRON2/3/4) distinct from the 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 experiment, single lab, single method\",\n      \"pmids\": [\"21237287\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Crystal structure of PfAMA1 in complex with a peptide derived from the extracellular region of PfRON2 was determined. The receptor-binding site of PfAMA1 comprises the hydrophobic groove and a region exposed by displacement of the flexible Domain II loop. Mutations of key contact residues in PfRON2 and PfAMA1 abrogate binding between the recombinant proteins. The PfRON2 peptide inhibits P. falciparum erythrocyte invasion, and this inhibitory potency is not affected by AMA1 polymorphisms. The R1 inhibitory peptide mimics the PfRON2 peptide structurally in binding to PfAMA1.\",\n      \"method\": \"X-ray crystallography, site-directed mutagenesis, binding assays, invasion inhibition assay\",\n      \"journal\": \"PLoS pathogens\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structure plus mutagenesis plus functional invasion inhibition assay in single rigorous study\",\n      \"pmids\": [\"22737069\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"In P. falciparum merozoites, RON2 (Rhoptry Neck Protein 2) is released early during invasion, following the junction, as determined by high-definition imaging of endogenously tagged proteins, supporting the model that RON2 is among the first rhoptry neck proteins secreted during invasion.\",\n      \"method\": \"Endogenous gene tagging, high-definition live and fixed fluorescence imaging\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — endogenous tagging with direct imaging showing secretion timing, single lab\",\n      \"pmids\": [\"23049965\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"A small molecule identified by high-throughput screening inhibits P. falciparum merozoite invasion by binding to AMA1 and blocking formation of the AMA1-RON2 complex; electron microscopy confirmed this inhibitor prevents tight junction formation, directly linking AMA1-RON2 complex formation to junction formation during invasion.\",\n      \"method\": \"High-throughput compound screening, binding assay, electron microscopy, invasion inhibition assay\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — multiple orthogonal methods (biochemical binding, EM junction morphology, functional invasion assay), mechanism directly demonstrated\",\n      \"pmids\": [\"23907321\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Live cell imaging with systematic blocking of receptor-ligand interactions established the temporal sequence of invasion: the AMA1-RON2 interaction mediates tight junction formation, which acts as an anchor point for parasite internalization, occurring after the PfRh5-basigin binding step.\",\n      \"method\": \"Live cell imaging, genetic deletion, enzymatic receptor cleavage, inhibitory antibodies and peptides\",\n      \"journal\": \"PLoS pathogens\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — systematic epistasis using multiple orthogonal blocking methods with live imaging, replicated across multiple invasion steps\",\n      \"pmids\": [\"25723550\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"The Domain II (DII) loop of PfAMA1 kinetically stabilizes the PfAMA1-RON2 complex by lengthening the complex half-life 18-fold (from ~48 s to ~900 s at 25°C) by slowing the dissociation rate, as determined by fluorescence anisotropy kinetic and thermodynamic measurements comparing wild-type PfAMA1 and a ΔDII-loop engineered construct.\",\n      \"method\": \"Fluorescence anisotropy kinetics, isothermal titration calorimetry, engineered deletion mutant\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro reconstitution with mutagenesis (deletion mutant), quantitative kinetics via two orthogonal methods, single lab\",\n      \"pmids\": [\"26731670\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"In P. berghei, RON2 (PBRON2) localizes to the rhoptries in merozoites and is also expressed in sporozoites with the same timing and apical rhoptry location as the known rhoptry protein RAP2/3, establishing RON2 rhoptry localization across both invasion stages.\",\n      \"method\": \"GFP/MYC epitope tagging, fluorescence microscopy, cross-lifecycle expression analysis\",\n      \"journal\": \"Molecular and biochemical parasitology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct localization by endogenous fluorescent tagging across multiple life cycle stages, single lab\",\n      \"pmids\": [\"19428669\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium berghei\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"In P. yoelii sporozoites, RON2 and RON4 are lost following rhoptry discharge during entry into host cells (analogous to merozoite entry), and rhoptry discharge of RON2/RON4 in sporozoites requires the host membrane protein CD81, as sporozoites failed to discharge rhoptries in CD81-negative conditions.\",\n      \"method\": \"Transgenic P. yoelii expressing fluorescent RON2/RON4/RAP2-3, fluorescence microscopy, CD81-dependent entry assay\",\n      \"journal\": \"Cellular microbiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct imaging of RON2 discharge in live transgenic parasites with genetic/host factor dependency established, single lab\",\n      \"pmids\": [\"24798694\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium yoelii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"In P. berghei, RON2 is localized to rhoptries in sporozoites. Sporozoite stage-specific knockdown of ron2 (by promoter swapping to restrict transcription to intraerythrocytic stages) severely impaired sporozoite invasion of mosquito salivary glands by decreasing attachment capacity, and also reduced infectivity to hepatocytes, demonstrating a functional role for RON2 in sporozoite invasion distinct from its role in merozoite invasion.\",\n      \"method\": \"Promoter swapping strategy for stage-specific knockdown, salivary gland invasion assay, hepatocyte infection assay, immunofluorescence\",\n      \"journal\": \"Cellular microbiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — stage-specific genetic knockdown with specific invasion phenotype quantified across two host cell types, multiple functional readouts\",\n      \"pmids\": [\"30307699\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium berghei\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"In P. berghei sporozoites, RON2 localizes to rhoptries (confirmed by immuno-electron microscopy). Unlike merozoites where RON2 and RON4 are neck-restricted, most rhoptry neck proteins including RON2 localize throughout the rhoptries in sporozoites, indicating stage-specific differences in subcompartmentalization.\",\n      \"method\": \"Immuno-electron microscopy, immunofluorescence assay\",\n      \"journal\": \"Frontiers in cellular and infection microbiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — immuno-EM with direct localization, single lab, single species\",\n      \"pmids\": [\"31552198\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium berghei\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"In P. berghei sporozoites, RON2, RON4, and RON5 form a complex (as demonstrated by co-immunoprecipitation from oocyst-derived sporozoite extracts). Stage-specific knockdown revealed that RON2 and RON4 reciprocally affect each other's trafficking to rhoptries in developing sporozoites, while RON5 is independently transported. RON4 and RON5 knockdown reduced sporozoite attachment and salivary gland invasion.\",\n      \"method\": \"Co-immunoprecipitation from sporozoite extracts, sporozoite stage-specific gene knockdown, salivary gland invasion assay, fluorescence microscopy\",\n      \"journal\": \"mSphere\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — co-IP from native sporozoite extracts plus reciprocal trafficking effects shown by genetic knockdown in two partners, multiple functional readouts\",\n      \"pmids\": [\"32817376\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium berghei\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"In P. berghei, conditional DiCre-mediated deletion of RON2 (or RON4) in sporozoites impairs 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 led to altered morphology of the entry junction, associated with epithelial cell damage, establishing that RON2 is required for forming a proper invasion junction in sporozoites.\",\n      \"method\": \"DiCre-mediated conditional gene deletion, mosquito salivary gland invasion assay, hepatocyte invasion assay, 3D electron microscopy\",\n      \"journal\": \"PLoS pathogens\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — conditional genetic KO with specific invasion phenotypes plus 3D-EM structural phenotype, multiple invasion stages, rigorous controls\",\n      \"pmids\": [\"35731833\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium berghei\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"In P. yoelii merozoites, PyRON2 was already present on the merozoite surface immediately after egress (prior to erythrocyte encounter), and its secretion was not affected by PKAc disruption, in contrast to AMA1. This is inconsistent with the model that RON2 is injected exclusively into the erythrocyte cytosol from within the host, suggesting RON2 may be exposed on the merozoite surface before invasion.\",\n      \"method\": \"DiCre-loxP inducible knockout of PKAc, immunofluorescence microscopy for RON2 localization at egress, erythrocyte invasion assay\",\n      \"journal\": \"Parasitology international\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct imaging at defined invasion stages using inducible KO system, single lab, single species, conflicts with current model\",\n      \"pmids\": [\"34390881\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium yoelii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"Cryo-EM structure of the endogenous P. falciparum moving junction purified from invasion-stalled parasites revealed a 1:1:1:1 assembly of PfAMA1 with PfRON2, PfRON4, and PfRON5. PfRON2 contains two transmembrane helices that anchor the complex in the red blood cell membrane and display an extracellular handle for PfAMA1 binding. PfAMA1 directly contacts the RBC membrane. PfRON2/4/5 form a large basic platform inside the RBC that electrostatically engages the RBC membrane and embeds amphipathic helices into the bilayer, suggesting RON2 participates in host membrane remodeling during invasion.\",\n      \"method\": \"Cryo-EM structural determination of endogenous complex purified from invasion-stalled P. falciparum, computational protein design of binder\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — near-atomic cryo-EM structure of endogenous complex with functional validation by designed inhibitor, rigorous methodology\",\n      \"pmids\": [\"42379167\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Computational simulation of DII loop dynamics in the PfAMA1-PfRON2 complex identified key residues in the PfRON2 helix essential for the post-binding lock conformation. Experimental mutagenesis of these residues validated their functional importance in complex stabilization.\",\n      \"method\": \"Molecular dynamics simulation, mutagenesis with experimental binding validation\",\n      \"journal\": \"Chembiochem : a European journal of chemical biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — computation guided mutagenesis with experimental binding validation, single lab, single study\",\n      \"pmids\": [\"40067319\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"For P. vivax RON2, the disulfide bond between C2051 and C2063 in the cyclic form of the PvRON2 peptide is essential for interaction with PvAMA1; the linear peptide lacking this bond showed no detectable interaction by SPR or ITC, establishing that the RON2 disulfide-constrained structure is required for AMA1 binding.\",\n      \"method\": \"Surface plasmon resonance, isothermal titration calorimetry, far western blot, circular dichroism, SAXS\",\n      \"journal\": \"Malaria journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — multiple biophysical methods (SPR, ITC, CD, SAXS) with direct structural requirement demonstrated by cyclic vs linear comparison, single lab\",\n      \"pmids\": [\"30683104\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium vivax\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Crystal structure of the complex formed between PvAMA1 and PvRON2sp1 peptide was determined. Binding studies showed PvRON2sp1 has strong cross-reactivity with PfAMA1, but PfRON2sp1 has no detectable interaction with PvAMA1; the species asymmetry was largely attributable to PvRON2-Thr2055 versus PfRON2-Arg2041.\",\n      \"method\": \"X-ray crystallography, surface plasmon resonance binding assays\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — crystal structures plus quantitative SPR binding data in single study, specific residue identified for species specificity\",\n      \"pmids\": [\"28817634\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium vivax\", \"strain\": \"\"}, {\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Specific residues in the β-hairpin loop of RON2 and specific residues in AMA1 Loop1E determine species-specific binding between AMA1 and RON2 in P. falciparum and P. vivax. Mutation of specific amino acids in AMA1 Loop1E in P. falciparum ablated RON2 binding without impacting erythrocyte invasion, demonstrating that the AMA1-RON2-loop interaction is NOT essential for invasion and that additional AMA1 interactions are involved.\",\n      \"method\": \"Site-directed mutagenesis of AMA1 and RON2, erythrocyte invasion assay, binding assays\",\n      \"journal\": \"Cellular and molecular life sciences : CMLS\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — mutagenesis of both binding partners with quantitative functional invasion readout, unexpected negative finding for essentiality of this interaction\",\n      \"pmids\": [\"36847896\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}, {\"species\": \"Plasmodium vivax\", \"strain\": \"\"}]\n    }\n  ],\n  \"current_model\": \"P. falciparum RON2 (PF3D7_1452000) is a rhoptry neck protein that, during merozoite invasion, is discharged and inserted as an integral membrane protein into the host erythrocyte membrane via two transmembrane helices; its extracellular loop binds the hydrophobic groove of the parasite surface protein AMA1 in a disulfide-dependent manner to form a 1:1:1:1 moving junction complex with RON4 and RON5, thereby anchoring the parasite to the erythrocyte and driving internalization, while the RON2/4/5 platform inside the RBC also participates in host membrane remodeling; RON2 similarly localizes to rhoptries in sporozoites, where it is required for invasion of both mosquito salivary glands and mammalian hepatocytes, and RON2 and RON4 reciprocally stabilize each other's trafficking to rhoptries.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"RON2 (PF3D7_1452000) is a rhoptry neck protein that serves as the parasite-supplied membrane anchor of the moving junction, the tight-junction structure through which apicomplexan parasites invade host cells [#0, #2]. In P. falciparum merozoites, RON2 localizes to the neck of the rhoptry, peaks in transcription at the mature schizont stage, and is discharged early during invasion, after which it is inserted as an integral membrane protein into the host erythrocyte membrane [#0, #2, #7]. Its extracellular region binds the hydrophobic groove of the parasite surface protein AMA1 in a manner that requires two conserved, disulfide-linked cysteines in the RON2 peptide, and this AMA1-RON2 engagement triggers tight-junction formation that anchors the parasite and commits the merozoite to invasion [#2, #3, #6]. Junction formation via AMA1-RON2 is a molecularly distinct step from parasitophorous vacuole formation and occurs downstream of the PfRh5-basigin binding step in the invasion sequence [#3, #9]. A cryo-EM structure of the endogenous complex shows a 1:1:1:1 assembly of AMA1 with RON2, RON4, and RON5, in which two RON2 transmembrane helices anchor the complex in the erythrocyte membrane and present an extracellular handle for AMA1 binding, while the RON2/4/5 platform inside the red cell electrostatically engages and embeds into the membrane bilayer, implicating RON2 in host membrane remodeling [#18]. Beyond its erythrocytic role, RON2 also localizes to rhoptries in sporozoites and is required for invasion of both mosquito salivary glands and mammalian hepatocytes, where loss of a functional AMA1-RON complex alters the entry junction morphology [#13, #16]. Notably, mutations in the AMA1 Loop1E that ablate RON2-loop binding do not impair erythrocyte invasion, indicating additional AMA1 interactions contribute and that the isolated AMA1-RON2 loop contact is not strictly essential [#22].\",\n  \"teleology\": [\n    {\n      \"year\": 2008,\n      \"claim\": \"Establishing that P. falciparum possesses a moving-junction complex was needed to test whether the apicomplexan invasion machinery is conserved beyond T. gondii; localizing RON2 to the rhoptry neck and showing it complexes with RON4 and AMA1 defined RON2 as a core junction component and excluded it from the RhopH complex.\",\n      \"evidence\": \"Co-immunoprecipitation, immunofluorescence, and transcriptional analysis in P. falciparum merozoites\",\n      \"pmids\": [\"18952195\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Interaction shown by Co-IP without stoichiometry or direct binding interface\", \"Functional requirement of RON2 for invasion not yet demonstrated\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Whether RON2 acts on the parasite or host side of the junction and whether its AMA1 contact is functionally required were unresolved; showing RON2 inserts as an integral host-membrane protein and mapping its AMA1-binding extracellular region with invasion-blocking assays established RON2 as the host-membrane-anchored receptor for AMA1 driving entry.\",\n      \"evidence\": \"Membrane insertion assay, native/recombinant interaction assays, and invasion inhibition in P. falciparum\",\n      \"pmids\": [\"21347343\", \"22033736\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular topology of the two transmembrane segments not yet defined\", \"Nature of the host-membrane insertion mechanism unresolved\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"The chemistry of the RON2-AMA1 interface and its precise role in the invasion sequence were unknown; identifying two disulfide-linked cysteines as critical for binding to the AMA1 hydrophobic pocket and showing the RON2 peptide blocks junction but not vacuole formation established that this interaction triggers a discrete commitment step.\",\n      \"evidence\": \"AMA1 pocket mutants, RON2 peptide competition, antibody blocking, and live imaging of junction versus vacuole formation in P. falciparum\",\n      \"pmids\": [\"21788485\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of the disulfide-constrained peptide binding not yet resolved at atomic level\", \"Relationship between RON2 peptide and full-length RON2 behavior not addressed\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Atomic-resolution understanding of how RON2 engages AMA1 and whether the interface is a drug target were needed; crystallography of the AMA1-RON2 peptide complex defined the hydrophobic groove plus Domain-II-loop-displaced site and showed the RON2 peptide inhibits invasion irrespective of AMA1 polymorphism.\",\n      \"evidence\": \"X-ray crystallography, site-directed mutagenesis, binding and invasion inhibition assays in P. falciparum\",\n      \"pmids\": [\"22737069\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Peptide-only structure does not capture the full-length transmembrane-anchored complex\", \"Kinetics of complex formation and stabilization not addressed\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"The timing of RON2 secretion relative to junction formation was uncertain; high-definition imaging of endogenously tagged RON2 showed it is released early, among the first rhoptry neck proteins secreted during invasion.\",\n      \"evidence\": \"Endogenous gene tagging with live and fixed high-definition fluorescence imaging in P. falciparum\",\n      \"pmids\": [\"23049965\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism of rhoptry discharge triggering not defined\", \"Whether secretion timing differs across species not addressed\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"The position of the AMA1-RON2 junction within the ordered invasion cascade was unresolved; systematic blocking with live imaging placed AMA1-RON2-mediated tight-junction formation downstream of PfRh5-basigin binding, defining it as the anchoring step for internalization.\",\n      \"evidence\": \"Live cell imaging with genetic deletion, receptor cleavage, and inhibitory antibodies/peptides in P. falciparum\",\n      \"pmids\": [\"25723550\", \"23907321\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular coupling between junction and the actomyosin motor not detailed\", \"How the junction physically anchors internalization not structurally defined\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Why the AMA1 Domain II loop matters for a productive junction was unclear; kinetic measurements showed the DII loop stabilizes the AMA1-RON2 complex 18-fold by slowing dissociation, revealing a post-binding locking mechanism.\",\n      \"evidence\": \"Fluorescence anisotropy kinetics, ITC, and a DII-loop deletion mutant in P. falciparum\",\n      \"pmids\": [\"26731670\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural conformation of the locked state not directly visualized\", \"Physiological consequence of altered half-life on invasion efficiency not quantified\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Whether the disulfide-constrained RON2 conformation is a general binding requirement across Plasmodium species was untested; comparison of cyclic versus linear PvRON2 peptides showed the C2051-C2063 disulfide is essential for PvAMA1 binding, and cross-species structural work identified single residues driving species-specific recognition.\",\n      \"evidence\": \"SPR, ITC, CD, SAXS with cyclic/linear peptide comparison in P. vivax; crystallography and SPR across P. vivax and P. falciparum\",\n      \"pmids\": [\"30683104\", \"28817634\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Species-specificity determinants tested largely with peptides, not full-length proteins\", \"Consequences for cross-species invasion in vivo not addressed\"],\n      \"attribution\": [{\"species\": \"Plasmodium vivax\", \"strain\": \"\"}, {\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Whether the AMA1-RON2 loop contact is strictly essential for invasion was assumed but untested; mutating AMA1 Loop1E to ablate RON2 binding without impairing erythrocyte invasion showed the isolated loop interaction is dispensable and that additional AMA1 contacts contribute.\",\n      \"evidence\": \"Site-directed mutagenesis of AMA1 and RON2 with erythrocyte invasion and binding assays in P. falciparum and P. vivax\",\n      \"pmids\": [\"36847896\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Identity of the compensating additional AMA1-RON2 contacts not defined\", \"Whether redundancy applies to sporozoite invasion not tested\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}, {\"species\": \"Plasmodium vivax\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Whether RON2 functions beyond the blood stage was unknown; in P. berghei, sporozoite-stage-specific ron2 knockdown impaired salivary gland invasion by reducing attachment and reduced hepatocyte infectivity, establishing a distinct RON2 role in sporozoite invasion.\",\n      \"evidence\": \"Promoter-swap stage-specific knockdown with salivary gland and hepatocyte invasion assays in P. berghei\",\n      \"pmids\": [\"30307699\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether sporozoite RON2 engages AMA1 in the same way as merozoite RON2 not established\", \"Direct binding partners at the sporozoite junction not defined\"],\n      \"attribution\": [{\"species\": \"Plasmodium berghei\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"How the sporozoite RON complex is assembled and trafficked was unknown; Co-IP from sporozoite extracts plus stage-specific knockdown showed RON2, RON4, and RON5 form a complex and that RON2 and RON4 reciprocally depend on each other for rhoptry trafficking, whereas RON5 is transported independently.\",\n      \"evidence\": \"Co-IP from oocyst-derived sporozoite extracts and stage-specific knockdown with invasion assays in P. berghei\",\n      \"pmids\": [\"32817376\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular basis of the reciprocal RON2/RON4 trafficking dependency not defined\", \"Whether the same interdependence operates in merozoites not tested\"],\n      \"attribution\": [{\"species\": \"Plasmodium berghei\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Whether RON2 is genuinely required to build a functional entry junction in sporozoites, versus merely present, was unresolved; conditional deletion of RON2 impaired salivary gland colonization and hepatocyte invasion without affecting transcellular migration, and 3D-EM revealed an altered entry junction morphology.\",\n      \"evidence\": \"DiCre conditional deletion with invasion assays and 3D electron microscopy in P. berghei\",\n      \"pmids\": [\"35731833\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural detail of the sporozoite junction at molecular resolution not defined\", \"Host receptor on salivary gland/hepatocyte engaged by the sporozoite RON complex not identified\"],\n      \"attribution\": [{\"species\": \"Plasmodium berghei\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"The architecture of the full endogenous moving junction and RON2's membrane role were unresolved; cryo-EM of the invasion-stalled complex revealed a 1:1:1:1 AMA1-RON2-RON4-RON5 assembly with two RON2 transmembrane helices anchoring the complex and a RON2/4/5 platform embedding into the RBC membrane, implicating RON2 in host membrane remodeling.\",\n      \"evidence\": \"Cryo-EM of endogenous complex purified from invasion-stalled P. falciparum with a computationally designed binder\",\n      \"pmids\": [\"42379167\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Dynamics of membrane insertion and remodeling not directly captured\", \"Mechanistic link between the basic platform and internalization force not defined\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"It remains unresolved whether RON2 is delivered exclusively into the host membrane from within the erythrocyte or is also exposed on the merozoite surface before invasion, and how these competing observations reconcile with the moving-junction model.\",\n      \"evidence\": \"P. yoelii imaging showed RON2 present on the merozoite surface immediately after egress and secreted independently of PKAc, contrasting with AMA1\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct visualization of RON2 topology during live invasion lacking\", \"Species differences (P. yoelii versus P. falciparum) may confound interpretation\", \"Timing of surface exposure relative to host-membrane insertion unresolved\"],\n      \"attribution\": [{\"species\": \"Plasmodium yoelii\", \"strain\": \"\"}]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0005515\", \"supporting_discovery_ids\": [0, 2, 3, 5, 6, 15, 18]},\n      {\"term_id\": \"GO:0046790\", \"supporting_discovery_ids\": [2, 4, 18]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0020008\", \"supporting_discovery_ids\": [0, 11, 13, 14]},\n      {\"term_id\": \"GO:0020005\", \"supporting_discovery_ids\": [2, 18]},\n      {\"term_id\": \"GO:0016020\", \"supporting_discovery_ids\": [2, 18]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0044409\", \"supporting_discovery_ids\": [2, 3, 9, 13, 16]},\n      {\"term_id\": \"GO:0006909\", \"supporting_discovery_ids\": [3, 8, 9]}\n    ],\n    \"complexes\": [\n      \"Moving junction complex: AMA1-RON2-RON4-RON5 (1:1:1:1) [#0, #18]\",\n      \"PfRON2/RON3/RON4 complex distinct from the moving junction [#5]\",\n      \"Sporozoite RON2/RON4/RON5 complex [#15]\"\n    ],\n    \"partners\": [\n      \"AMA1 (binds RON2 extracellular region via hydrophobic groove) [#2, #3, #4, #6]\",\n      \"RON4 (complex partner; reciprocal trafficking dependency in sporozoites) [#0, #15]\",\n      \"RON5 (moving junction and sporozoite complex partner) [#15, #18]\",\n      \"RON3 (PfRON2/3/4 complex) [#5]\",\n      \"Host erythrocyte membrane (integral insertion; C-terminal cysteine-rich domain binds erythrocytes) [#2, #4, #18]\"\n    ],\n    \"other_free_text\": [\n      \"Two conserved disulfide-linked cysteines in the RON2 peptide are critical for AMA1 hydrophobic-pocket binding [#3]; disulfide-constrained cyclic conformation required for AMA1 binding in P. vivax [#20].\",\n      \"AMA1 Domain II loop kinetically stabilizes the AMA1-RON2 complex ~18-fold by slowing dissociation [#10]; specific RON2 helix residues mediate a post-binding lock conformation [#19].\",\n      \"AMA1 Loop1E mutations that ablate RON2-loop binding do not impair erythrocyte invasion, indicating the isolated loop contact is not essential and additional AMA1 interactions contribute [#22].\",\n      \"Two RON2 transmembrane helices anchor the complex in the RBC membrane; the intracellular RON2/4/5 platform embeds amphipathic helices, implicating RON2 in host membrane remodeling [#18].\",\n      \"Sporozoite rhoptry discharge of RON2/RON4 requires host CD81 in P. yoelii [#12]; sporozoite RON2 distributes throughout the rhoptry rather than being neck-restricted as in merozoites [#14].\",\n      \"Species-specific AMA1-RON2 recognition maps to single residues (e.g. PvRON2-Thr2055 vs PfRON2-Arg2041) [#21].\",\n      \"In P. yoelii, RON2 was detected on the merozoite surface after egress and secreted independently of PKAc, conflicting with exclusive host-cytosol injection [#17].\"\n    ]\n  }\n}","audit_flag":null,"strains":[{"strain":"Pf3D7","gene_id":"PF3D7_1452000","name":null,"product":"rhoptry neck protein 2","uniprot_acc":null,"chromosome":null,"start_pos":null},{"strain":"PbANKA","gene_id":"PBANKA_1315700","name":null,"product":"rhoptry neck protein 2","uniprot_acc":null,"chromosome":null,"start_pos":null},{"strain":"PkH","gene_id":"PKNH_1230100","name":null,"product":"rhoptry neck protein 2, putative","uniprot_acc":null,"chromosome":null,"start_pos":null}],"gene_symbol":"RON2","evaluation":null}