{"gene":"PF3D7_0102500","run_date":"2026-09-07T10:55:51","timeline":{"discoveries":[{"year":2003,"finding":"EBA181 (PF3D7_0102500) is expressed in the microneme organelles of asexual stage P. falciparum parasites, co-localizing with EBA-175; it binds erythrocytes in a sialic acid-dependent, trypsin-resistant and chymotrypsin-sensitive manner; its receptor on erythrocytes is distinct from glycophorin B; and the gene can be disrupted in W2mef but not 3D7 parasites, indicating strain-dependent importance for invasion.","method":"Co-localization by immunofluorescence, erythrocyte binding assays with enzyme-treated and glycophorin B-deficient erythrocytes, gene disruption/targeted knockout","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (localization, binding assay, genetic disruption) in a single focused study, foundational characterization replicated in subsequent work","pmids":["12556470"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":"W2mef, 3D7"}]},{"year":2004,"finding":"Polymorphisms in region II (the erythrocyte-binding domain) of EBA181 across natural P. falciparum isolates produce at least four distinct erythrocyte-binding patterns when expressed on Chinese hamster ovary cells, demonstrating that single amino acid changes alter receptor specificity and allow recognition of multiple erythrocyte surface receptors.","method":"Sequencing of region II from 20 isolates; transient expression of region II variants on CHO cell surface followed by erythrocyte binding assays with enzyme-treated erythrocytes","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — functional binding assay with expressed recombinant domain variants across six isolates, single lab but multiple variants tested with orthogonal enzyme treatments","pmids":["14983041"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2005,"finding":"Synthetic 20-mer peptides derived from the N-terminal region of EBA181 bind specifically to erythrocyte surface receptors of ~53 kDa and ~33 kDa; this binding is enzyme-sensitive, concentration-dependent, and saturable; and these peptides inhibit P. falciparum merozoite invasion in vitro.","method":"Receptor-ligand binding assays with synthetic peptides and enzyme-treated erythrocytes; equilibrium binding parameter determination; in vitro merozoite invasion inhibition assays","journal":"Biochimie","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vitro binding assays and invasion inhibition, single lab, multiple orthogonal methods (binding kinetics + inhibition assay)","pmids":["15820749"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2006,"finding":"The 10 kDa domain of human erythrocyte membrane protein 4.1 (4.1R) specifically binds EBA181; the interaction is concentration-dependent, saturable, and abolished by heat denaturation of 4.1R.","method":"Blot overlay and histidine pull-down assays using recombinant proteins corresponding to the four structural domains of 4.1R and the 4.1R-binding region of EBA181","journal":"Malaria journal","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — two orthogonal in vitro methods (blot overlay + pull-down) with recombinant proteins, single lab","pmids":["17087826"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2009,"finding":"Polymorphisms in the region II binding domain of EBA181 affect the level of erythrocyte binding but do not alter receptor specificity; the degree of binding correlates with invasion function, paralleling results for EBA-140 but contrasting with EBA-175.","method":"Erythrocyte binding assays with recombinant region II constructs from polymorphic isolates; invasion assays comparing parental and variant parasite lines","journal":"Infection and immunity","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — binding and invasion assays across multiple polymorphic variants, single lab, two orthogonal functional readouts","pmids":["19204093"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2010,"finding":"Loss of EBA181 function (gene knockout) ablates the ability of PfRh2a/b antibodies to inhibit merozoite invasion, demonstrating a functional interaction between EBA181 and the PfRh2a/b proteins; additionally, disruption of eba181 results in selection for increased transcription of PfRh family genes, indicating cooperative and compensatory relationships between EBL and PfRh invasion ligands.","method":"Single and double gene knockouts of eba-175, eba-181, and eba-140; invasion inhibition assays with anti-PfRh2a/b antibodies; quantitative transcriptional analysis of PfRh family genes","journal":"Infection and immunity","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic knockouts combined with antibody inhibition assays and transcriptional analysis; replicated across multiple knockout combinations in the same study","pmids":["21149582"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2013,"finding":"EBA181 binds heparin; heparin-binding by EBA181 (and other apical surface proteins) localizes to the apical tip of the merozoite, and heparin affinity chromatography demonstrated that EBA181 is among the Duffy binding-like family members that bind heparin with diverse affinities.","method":"Heparin affinity chromatography fractionation of parasite proteins; immunoblot analysis with ligand-specific antibodies; immunofluorescence localization","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — affinity chromatography combined with immunoblot and localization, single lab, two orthogonal approaches","pmids":["24212193"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2013,"finding":"EBA181 is a target of naturally acquired human invasion-inhibitory antibodies; P. falciparum lines with eba181 gene disruption show reduced sensitivity to inhibitory antibodies from malaria-exposed individuals compared to parental parasites, indicating that EBA181 expression contributes to immune evasion through variation in function.","method":"Invasion inhibition assays using plasma from malaria-exposed children and adults against parental and EBA181 (and EBA140, EBA175) single and double knockout P. falciparum lines","journal":"Journal of immunology (Baltimore, Md. : 1950)","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic knockouts with functional invasion inhibition assays, tested with human immune sera from two geographically distinct populations","pmids":["23776178"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2014,"finding":"The RIII-V domains of EBA181 (residues 945–1097) are intrinsically disordered; NMR spectroscopy revealed that this region is essentially a statistical coil with several turn motifs and lacks transiently populated secondary structures typical of disordered proteins that fold via pre-formed recognition elements.","method":"Bioinformatics disorder prediction; biophysical characterization including NMR spectroscopy at atomic resolution of recombinant EBA-181945-1097 construct","journal":"Biochimica et biophysica acta","confidence":"High","confidence_rationale":"Tier 1 / Moderate — atomic-resolution NMR structural characterization with supporting bioinformatics and biophysical methods, single lab","pmids":["25288451"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2022,"finding":"EBA181 gene expression is stochastically variable among individual P. falciparum schizonts, as confirmed by quantitative RT-PCR and RNA-FISH at the single-cell level, suggesting epigenetic regulation of its transcription.","method":"Single-cell RNA sequencing (MALBAC-based amplification), quantitative RT-PCR, RNA-FISH","journal":"Nature communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — single-cell sequencing validated by two orthogonal methods (qRT-PCR and RNA-FISH), single lab","pmids":["35637187"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2025,"finding":"EBA181 binds to Neu5Ac and Neu5Gc sialic acids; interacts with the merozoite Rh2b protein with a dissociation constant of approximately 3 µM (measured by Surface Plasmon Resonance); and binds to an ~100 kDa erythrocyte membrane protein, with Band 3 protein proposed as a putative erythrocyte receptor.","method":"Surface Plasmon Resonance with recombinant EBA-181 ligand against sugar moieties, Rh2b protein, and erythrocyte membrane fractions","journal":"Parasitology research","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — direct binding measurements by SPR with defined KD, single lab, single method; receptor identity (Band 3) remains putative","pmids":["41198968"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]}],"current_model":"EBA181 (PF3D7_0102500) is a P. falciparum microneme-localized erythrocyte binding-like protein that mediates a sialic acid-dependent, trypsin-resistant/chymotrypsin-sensitive invasion pathway by binding erythrocyte surface receptors through its region II domain (with polymorphisms affecting binding level but not necessarily receptor specificity), interacts with erythrocyte protein 4.1R via its 10 kDa domain, physically associates with the merozoite Rh2b ligand (~3 µM KD), functionally cooperates with PfRh proteins during invasion, contains intrinsically disordered RIII-V domains, is expressed stochastically among schizonts, and serves as a target of naturally acquired invasion-inhibitory antibodies whose evasion is facilitated by variation in EBA181 expression."},"narrative":{"mechanistic_narrative":"EBA181 (PF3D7_0102500) is a microneme-localized member of the P. falciparum erythrocyte binding-like family that mediates a sialic acid-dependent, trypsin-resistant/chymotrypsin-sensitive pathway of merozoite invasion into erythrocytes [PMID:12556470]. It engages erythrocyte surface receptors through its region II binding domain, where natural polymorphisms modulate the level of erythrocyte binding in a manner that correlates with invasion function [PMID:19204093]; its N-terminal region binds specific erythrocyte surface proteins, and peptides from this region block invasion in vitro [PMID:15820749]. On the host side EBA181 recognizes Neu5Ac and Neu5Gc sialic acids and an ~100 kDa erythrocyte membrane protein, and it binds the erythrocyte cytoskeletal adaptor 4.1R through its 10 kDa domain [PMID:17087826, PMID:41198968]. Rather than acting in isolation, EBA181 functionally cooperates with the PfRh invasion ligands: its physical association with Rh2b (KD ~3 µM) [PMID:41198968] and the finding that eba181 knockout abolishes anti-PfRh2a/b antibody inhibition and drives compensatory upregulation of PfRh genes [PMID:21149582] place it within an interdependent EBL/PfRh invasion network. EBA181 is dispensable in some strains (disruptable in W2mef but not 3D7) [PMID:12556470], is expressed stochastically among schizonts consistent with epigenetic control [PMID:35637187], and is a target of naturally acquired invasion-inhibitory antibodies whose evasion is aided by variation in EBA181 expression [PMID:23776178]. Its RIII-V region is intrinsically disordered [PMID:25288451].","teleology":[{"year":2003,"claim":"Established EBA181 as a bona fide invasion ligand by placing it in the micronemes and defining the biochemical signature of its erythrocyte binding, answering where and how the protein acts during invasion.","evidence":"Immunofluorescence co-localization with EBA-175, erythrocyte binding assays with enzyme-treated and glycophorin B-deficient cells, and gene disruption in W2mef versus 3D7","pmids":["12556470"],"confidence":"High","gaps":["Molecular identity of the erythrocyte receptor left undefined beyond being distinct from glycophorin B","Basis of strain-dependent dispensability (W2mef vs 3D7) not resolved"],"attribution":[{"species":"Plasmodium falciparum","strain":"W2mef, 3D7"}]},{"year":2004,"claim":"Addressed whether sequence variation in the binding domain changes what EBA181 recognizes, testing how the parasite might diversify receptor usage.","evidence":"Sequencing of region II from natural isolates and CHO-cell surface expression of region II variants assayed against enzyme-treated erythrocytes","pmids":["14983041"],"confidence":"High","gaps":["Later work reinterpreted these effects as altering binding level rather than specificity","Receptor(s) recognized by each variant not identified"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2005,"claim":"Mapped functional binding activity to the N-terminal region and demonstrated its causal role in invasion by peptide inhibition.","evidence":"Synthetic 20-mer peptide binding to ~53 and ~33 kDa erythrocyte receptors with saturable kinetics and in vitro merozoite invasion inhibition","pmids":["15820749"],"confidence":"Medium","gaps":["The ~53/~33 kDa receptor proteins were not molecularly identified","Peptide inhibition does not establish which region drives receptor engagement in the native protein"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2006,"claim":"Identified an intracellular host partner, showing EBA181 engages the erythrocyte cytoskeletal adaptor 4.1R and hinting at a role beyond a simple surface receptor.","evidence":"Blot overlay and histidine pull-down assays with recombinant 4.1R domains and the EBA181 binding region","pmids":["17087826"],"confidence":"Medium","gaps":["Functional consequence of the 4.1R interaction during invasion not tested","In vitro binding not confirmed in situ within intact erythrocytes"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2009,"claim":"Refined the earlier polymorphism model, showing region II variation tunes binding strength rather than specificity and that binding level tracks with invasion function.","evidence":"Erythrocyte binding assays with recombinant region II from polymorphic isolates paired with invasion assays of variant parasite lines","pmids":["19204093"],"confidence":"Medium","gaps":["Structural basis for polymorphism-dependent binding-level differences not resolved","Single receptor identity underlying the binding still unknown"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2010,"claim":"Placed EBA181 in a functionally interdependent network with PfRh ligands, explaining how EBL and PfRh pathways cooperate and compensate during invasion.","evidence":"Single/double knockouts of eba genes, anti-PfRh2a/b antibody invasion inhibition assays, and quantitative PfRh transcriptional analysis","pmids":["21149582"],"confidence":"High","gaps":["Molecular basis of the functional link between EBA181 and PfRh2a/b left unresolved at this stage","Whether the cooperation is physical or purely functional not determined here"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2013,"claim":"Showed EBA181 is a heparin-binding apical protein, adding a biochemical property relevant to invasion-blocking by sulfated glycans.","evidence":"Heparin affinity chromatography with ligand-specific immunoblotting and immunofluorescence localization to the merozoite apical tip","pmids":["24212193"],"confidence":"Medium","gaps":["Whether heparin binding is physiologically relevant or an in vitro cross-reactivity not established","Heparin-binding site within EBA181 not mapped"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2013,"claim":"Demonstrated immunological relevance by showing EBA181 is a target of naturally acquired inhibitory antibodies and that its variable expression aids immune evasion.","evidence":"Invasion inhibition assays with plasma from malaria-exposed individuals against parental and eba knockout lines from two populations","pmids":["23776178"],"confidence":"High","gaps":["Epitopes recognized by protective antibodies not defined","Contribution of EBA181 antibodies to clinical protection in vivo not established"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2014,"claim":"Characterized the RIII-V region as intrinsically disordered, informing how this part of the protein behaves structurally.","evidence":"Disorder prediction and atomic-resolution NMR of the recombinant EBA181 residue 945-1097 construct","pmids":["25288451"],"confidence":"High","gaps":["Functional role of the disordered RIII-V region during invasion not defined","Whether disorder mediates partner interactions untested"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2022,"claim":"Revealed that eba181 transcription is stochastically variable across single schizonts, implicating epigenetic regulation as a source of the expression variation underlying immune evasion.","evidence":"Single-cell RNA sequencing validated by quantitative RT-PCR and RNA-FISH","pmids":["35637187"],"confidence":"Medium","gaps":["The specific epigenetic marks or regulators controlling eba181 not identified","Direct link between transcriptional variation and invasion phenotype not tested in this study"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2025,"claim":"Provided direct affinity measurements defining EBA181's molecular partners, including a physical Rh2b interaction that substantiates the earlier functional EBL/PfRh cooperation.","evidence":"Surface Plasmon Resonance of recombinant EBA181 against Neu5Ac/Neu5Gc sialic acids, Rh2b protein (KD ~3 µM), and erythrocyte membrane fractions","pmids":["41198968"],"confidence":"Medium","gaps":["Band 3 as the ~100 kDa erythrocyte receptor remains putative","Single-method (SPR) measurements not independently confirmed","Structural basis of the EBA181-Rh2b interaction unknown"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":null,"claim":"The definitive molecular identity of the erythrocyte surface receptor for EBA181 and the structural basis of its cooperation with PfRh2b remain unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No confirmed erythrocyte receptor identity (Band 3 still putative)","No structure of an EBA181-receptor or EBA181-Rh2b complex","Functional role of 4.1R binding and disordered RIII-V region in invasion undefined"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]}],"mechanism_profile":{"molecular_activity":[],"localization":[],"pathway":[],"complexes":[],"partners":["ERYTHROCYTE MEMBRANE PROTEIN 4.1 (4.1R) 10 KDA DOMAIN [#3]","PFRH2A/B — FUNCTIONAL COOPERATION [#5]","RH2B MEROZOITE PROTEIN — DIRECT BINDING, KD ~3 ΜM [#10]","NEU5AC / NEU5GC SIALIC ACIDS [#10]","~100 KDA ERYTHROCYTE MEMBRANE PROTEIN (BAND 3 PUTATIVE) [#10]","~53 KDA AND ~33 KDA ERYTHROCYTE SURFACE RECEPTORS [#2]"],"other_free_text":["Region II is the erythrocyte-binding domain; polymorphisms alter binding level (later model) with binding level correlating with invasion function [#1, #4]","RIII-V region (residues 945-1097) is intrinsically disordered by NMR [#8]","Sialic acid-dependent, trypsin-resistant, chymotrypsin-sensitive binding phenotype; receptor distinct from glycophorin B [#0]","Gene disruptable in W2mef but not 3D7, indicating strain-dependent importance [#0]","Stochastic single-cell expression among schizonts consistent with epigenetic regulation [#9]","Target of naturally acquired invasion-inhibitory antibodies; expression variation aids immune evasion [#7]"]}},"prefetch_data":{},"corpus_meta":[{"pmid":"20843207","id":"PMC_20843207","title":"Association between naturally acquired antibodies to erythrocyte-binding antigens of Plasmodium falciparum and protection from malaria and high-density parasitemia.","date":"2010","source":"Clinical infectious diseases : an official publication of the Infectious Diseases Society of 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(Online)","url":"https://pubmed.ncbi.nlm.nih.gov/21160096","citation_count":7,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["EBA181"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"24834503","id":"PMC_24834503","title":"Patterns of selection on Plasmodium falciparum erythrocyte-binding antigens after the colonization of the New World.","date":"2014","source":"Molecular ecology","url":"https://pubmed.ncbi.nlm.nih.gov/24834503","citation_count":6,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["EBA181"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"36812236","id":"PMC_36812236","title":"Effects of anti-malarial prophylaxes on maternal transfer of Immunoglobulin-G (IgG) and association to immunity against Plasmodium falciparum infections among children in a Ugandan birth cohort.","date":"2023","source":"PloS 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vectors","url":"https://pubmed.ncbi.nlm.nih.gov/37653544","citation_count":1,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["EBA181"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"41295464","id":"PMC_41295464","title":"A Multiplex Serological Assay to Evaluate the Antibody Responses to a Set of Plasmodium falciparum Antigens and Their Protective Role Against Malaria in Children Aged 1.5 to 12 Years Living in a Highly Seasonal Malaria Transmission Area of Burkina Faso.","date":"2025","source":"Vaccines","url":"https://pubmed.ncbi.nlm.nih.gov/41295464","citation_count":1,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["EBA181"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"42190989","id":"PMC_42190989","title":"Plasmodium falciparum invasion ligand gene transcript profiles in different populations.","date":"2026","source":"Molecular and biochemical parasitology","url":"https://pubmed.ncbi.nlm.nih.gov/42190989","citation_count":0,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["EBA181"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"41198968","id":"PMC_41198968","title":"P. falciparum EBA-181 ligand - searching for the receptor on human erythrocytes.","date":"2025","source":"Parasitology research","url":"https://pubmed.ncbi.nlm.nih.gov/41198968","citation_count":0,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["EBA181"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":20325,"output_tokens":3102,"usd":0.053753,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":8859,"output_tokens":4399,"usd":0.077135,"stage2_stop_reason":"end_turn"},"total_usd":0.130888,"stage1_batch_id":"msgbatch_01DbiymDmubkPpYvdbAu5a7V","stage2_batch_id":"msgbatch_012TbrWvMRH129T7PQ4SmvrJ","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2003,\n      \"finding\": \"EBA181 (PF3D7_0102500) is expressed in the microneme organelles of asexual stage P. falciparum parasites, co-localizing with EBA-175; it binds erythrocytes in a sialic acid-dependent, trypsin-resistant and chymotrypsin-sensitive manner; its receptor on erythrocytes is distinct from glycophorin B; and the gene can be disrupted in W2mef but not 3D7 parasites, indicating strain-dependent importance for invasion.\",\n      \"method\": \"Co-localization by immunofluorescence, erythrocyte binding assays with enzyme-treated and glycophorin B-deficient erythrocytes, gene disruption/targeted knockout\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (localization, binding assay, genetic disruption) in a single focused study, foundational characterization replicated in subsequent work\",\n      \"pmids\": [\"12556470\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"W2mef, 3D7\"}]\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Polymorphisms in region II (the erythrocyte-binding domain) of EBA181 across natural P. falciparum isolates produce at least four distinct erythrocyte-binding patterns when expressed on Chinese hamster ovary cells, demonstrating that single amino acid changes alter receptor specificity and allow recognition of multiple erythrocyte surface receptors.\",\n      \"method\": \"Sequencing of region II from 20 isolates; transient expression of region II variants on CHO cell surface followed by erythrocyte binding assays with enzyme-treated erythrocytes\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — functional binding assay with expressed recombinant domain variants across six isolates, single lab but multiple variants tested with orthogonal enzyme treatments\",\n      \"pmids\": [\"14983041\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Synthetic 20-mer peptides derived from the N-terminal region of EBA181 bind specifically to erythrocyte surface receptors of ~53 kDa and ~33 kDa; this binding is enzyme-sensitive, concentration-dependent, and saturable; and these peptides inhibit P. falciparum merozoite invasion in vitro.\",\n      \"method\": \"Receptor-ligand binding assays with synthetic peptides and enzyme-treated erythrocytes; equilibrium binding parameter determination; in vitro merozoite invasion inhibition assays\",\n      \"journal\": \"Biochimie\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vitro binding assays and invasion inhibition, single lab, multiple orthogonal methods (binding kinetics + inhibition assay)\",\n      \"pmids\": [\"15820749\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"The 10 kDa domain of human erythrocyte membrane protein 4.1 (4.1R) specifically binds EBA181; the interaction is concentration-dependent, saturable, and abolished by heat denaturation of 4.1R.\",\n      \"method\": \"Blot overlay and histidine pull-down assays using recombinant proteins corresponding to the four structural domains of 4.1R and the 4.1R-binding region of EBA181\",\n      \"journal\": \"Malaria journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — two orthogonal in vitro methods (blot overlay + pull-down) with recombinant proteins, single lab\",\n      \"pmids\": [\"17087826\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Polymorphisms in the region II binding domain of EBA181 affect the level of erythrocyte binding but do not alter receptor specificity; the degree of binding correlates with invasion function, paralleling results for EBA-140 but contrasting with EBA-175.\",\n      \"method\": \"Erythrocyte binding assays with recombinant region II constructs from polymorphic isolates; invasion assays comparing parental and variant parasite lines\",\n      \"journal\": \"Infection and immunity\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — binding and invasion assays across multiple polymorphic variants, single lab, two orthogonal functional readouts\",\n      \"pmids\": [\"19204093\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Loss of EBA181 function (gene knockout) ablates the ability of PfRh2a/b antibodies to inhibit merozoite invasion, demonstrating a functional interaction between EBA181 and the PfRh2a/b proteins; additionally, disruption of eba181 results in selection for increased transcription of PfRh family genes, indicating cooperative and compensatory relationships between EBL and PfRh invasion ligands.\",\n      \"method\": \"Single and double gene knockouts of eba-175, eba-181, and eba-140; invasion inhibition assays with anti-PfRh2a/b antibodies; quantitative transcriptional analysis of PfRh family genes\",\n      \"journal\": \"Infection and immunity\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic knockouts combined with antibody inhibition assays and transcriptional analysis; replicated across multiple knockout combinations in the same study\",\n      \"pmids\": [\"21149582\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"EBA181 binds heparin; heparin-binding by EBA181 (and other apical surface proteins) localizes to the apical tip of the merozoite, and heparin affinity chromatography demonstrated that EBA181 is among the Duffy binding-like family members that bind heparin with diverse affinities.\",\n      \"method\": \"Heparin affinity chromatography fractionation of parasite proteins; immunoblot analysis with ligand-specific antibodies; immunofluorescence localization\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — affinity chromatography combined with immunoblot and localization, single lab, two orthogonal approaches\",\n      \"pmids\": [\"24212193\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"EBA181 is a target of naturally acquired human invasion-inhibitory antibodies; P. falciparum lines with eba181 gene disruption show reduced sensitivity to inhibitory antibodies from malaria-exposed individuals compared to parental parasites, indicating that EBA181 expression contributes to immune evasion through variation in function.\",\n      \"method\": \"Invasion inhibition assays using plasma from malaria-exposed children and adults against parental and EBA181 (and EBA140, EBA175) single and double knockout P. falciparum lines\",\n      \"journal\": \"Journal of immunology (Baltimore, Md. : 1950)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic knockouts with functional invasion inhibition assays, tested with human immune sera from two geographically distinct populations\",\n      \"pmids\": [\"23776178\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"The RIII-V domains of EBA181 (residues 945–1097) are intrinsically disordered; NMR spectroscopy revealed that this region is essentially a statistical coil with several turn motifs and lacks transiently populated secondary structures typical of disordered proteins that fold via pre-formed recognition elements.\",\n      \"method\": \"Bioinformatics disorder prediction; biophysical characterization including NMR spectroscopy at atomic resolution of recombinant EBA-181945-1097 construct\",\n      \"journal\": \"Biochimica et biophysica acta\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — atomic-resolution NMR structural characterization with supporting bioinformatics and biophysical methods, single lab\",\n      \"pmids\": [\"25288451\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"EBA181 gene expression is stochastically variable among individual P. falciparum schizonts, as confirmed by quantitative RT-PCR and RNA-FISH at the single-cell level, suggesting epigenetic regulation of its transcription.\",\n      \"method\": \"Single-cell RNA sequencing (MALBAC-based amplification), quantitative RT-PCR, RNA-FISH\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — single-cell sequencing validated by two orthogonal methods (qRT-PCR and RNA-FISH), single lab\",\n      \"pmids\": [\"35637187\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"EBA181 binds to Neu5Ac and Neu5Gc sialic acids; interacts with the merozoite Rh2b protein with a dissociation constant of approximately 3 µM (measured by Surface Plasmon Resonance); and binds to an ~100 kDa erythrocyte membrane protein, with Band 3 protein proposed as a putative erythrocyte receptor.\",\n      \"method\": \"Surface Plasmon Resonance with recombinant EBA-181 ligand against sugar moieties, Rh2b protein, and erythrocyte membrane fractions\",\n      \"journal\": \"Parasitology research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — direct binding measurements by SPR with defined KD, single lab, single method; receptor identity (Band 3) remains putative\",\n      \"pmids\": [\"41198968\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    }\n  ],\n  \"current_model\": \"EBA181 (PF3D7_0102500) is a P. falciparum microneme-localized erythrocyte binding-like protein that mediates a sialic acid-dependent, trypsin-resistant/chymotrypsin-sensitive invasion pathway by binding erythrocyte surface receptors through its region II domain (with polymorphisms affecting binding level but not necessarily receptor specificity), interacts with erythrocyte protein 4.1R via its 10 kDa domain, physically associates with the merozoite Rh2b ligand (~3 µM KD), functionally cooperates with PfRh proteins during invasion, contains intrinsically disordered RIII-V domains, is expressed stochastically among schizonts, and serves as a target of naturally acquired invasion-inhibitory antibodies whose evasion is facilitated by variation in EBA181 expression.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"EBA181 (PF3D7_0102500) is a microneme-localized member of the P. falciparum erythrocyte binding-like family that mediates a sialic acid-dependent, trypsin-resistant/chymotrypsin-sensitive pathway of merozoite invasion into erythrocytes [#0]. It engages erythrocyte surface receptors through its region II binding domain, where natural polymorphisms modulate the level of erythrocyte binding in a manner that correlates with invasion function [#4]; its N-terminal region binds specific erythrocyte surface proteins, and peptides from this region block invasion in vitro [#2]. On the host side EBA181 recognizes Neu5Ac and Neu5Gc sialic acids and an ~100 kDa erythrocyte membrane protein, and it binds the erythrocyte cytoskeletal adaptor 4.1R through its 10 kDa domain [#3, #10]. Rather than acting in isolation, EBA181 functionally cooperates with the PfRh invasion ligands: its physical association with Rh2b (KD ~3 µM) [#10] and the finding that eba181 knockout abolishes anti-PfRh2a/b antibody inhibition and drives compensatory upregulation of PfRh genes [#5] place it within an interdependent EBL/PfRh invasion network. EBA181 is dispensable in some strains (disruptable in W2mef but not 3D7) [#0], is expressed stochastically among schizonts consistent with epigenetic control [#9], and is a target of naturally acquired invasion-inhibitory antibodies whose evasion is aided by variation in EBA181 expression [#7]. Its RIII-V region is intrinsically disordered [#8].\",\n  \"teleology\": [\n    {\n      \"year\": 2003,\n      \"claim\": \"Established EBA181 as a bona fide invasion ligand by placing it in the micronemes and defining the biochemical signature of its erythrocyte binding, answering where and how the protein acts during invasion.\",\n      \"evidence\": \"Immunofluorescence co-localization with EBA-175, erythrocyte binding assays with enzyme-treated and glycophorin B-deficient cells, and gene disruption in W2mef versus 3D7\",\n      \"pmids\": [\"12556470\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular identity of the erythrocyte receptor left undefined beyond being distinct from glycophorin B\", \"Basis of strain-dependent dispensability (W2mef vs 3D7) not resolved\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"W2mef, 3D7\"}]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Addressed whether sequence variation in the binding domain changes what EBA181 recognizes, testing how the parasite might diversify receptor usage.\",\n      \"evidence\": \"Sequencing of region II from natural isolates and CHO-cell surface expression of region II variants assayed against enzyme-treated erythrocytes\",\n      \"pmids\": [\"14983041\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Later work reinterpreted these effects as altering binding level rather than specificity\", \"Receptor(s) recognized by each variant not identified\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Mapped functional binding activity to the N-terminal region and demonstrated its causal role in invasion by peptide inhibition.\",\n      \"evidence\": \"Synthetic 20-mer peptide binding to ~53 and ~33 kDa erythrocyte receptors with saturable kinetics and in vitro merozoite invasion inhibition\",\n      \"pmids\": [\"15820749\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"The ~53/~33 kDa receptor proteins were not molecularly identified\", \"Peptide inhibition does not establish which region drives receptor engagement in the native protein\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Identified an intracellular host partner, showing EBA181 engages the erythrocyte cytoskeletal adaptor 4.1R and hinting at a role beyond a simple surface receptor.\",\n      \"evidence\": \"Blot overlay and histidine pull-down assays with recombinant 4.1R domains and the EBA181 binding region\",\n      \"pmids\": [\"17087826\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional consequence of the 4.1R interaction during invasion not tested\", \"In vitro binding not confirmed in situ within intact erythrocytes\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Refined the earlier polymorphism model, showing region II variation tunes binding strength rather than specificity and that binding level tracks with invasion function.\",\n      \"evidence\": \"Erythrocyte binding assays with recombinant region II from polymorphic isolates paired with invasion assays of variant parasite lines\",\n      \"pmids\": [\"19204093\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Structural basis for polymorphism-dependent binding-level differences not resolved\", \"Single receptor identity underlying the binding still unknown\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Placed EBA181 in a functionally interdependent network with PfRh ligands, explaining how EBL and PfRh pathways cooperate and compensate during invasion.\",\n      \"evidence\": \"Single/double knockouts of eba genes, anti-PfRh2a/b antibody invasion inhibition assays, and quantitative PfRh transcriptional analysis\",\n      \"pmids\": [\"21149582\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular basis of the functional link between EBA181 and PfRh2a/b left unresolved at this stage\", \"Whether the cooperation is physical or purely functional not determined here\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Showed EBA181 is a heparin-binding apical protein, adding a biochemical property relevant to invasion-blocking by sulfated glycans.\",\n      \"evidence\": \"Heparin affinity chromatography with ligand-specific immunoblotting and immunofluorescence localization to the merozoite apical tip\",\n      \"pmids\": [\"24212193\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether heparin binding is physiologically relevant or an in vitro cross-reactivity not established\", \"Heparin-binding site within EBA181 not mapped\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Demonstrated immunological relevance by showing EBA181 is a target of naturally acquired inhibitory antibodies and that its variable expression aids immune evasion.\",\n      \"evidence\": \"Invasion inhibition assays with plasma from malaria-exposed individuals against parental and eba knockout lines from two populations\",\n      \"pmids\": [\"23776178\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Epitopes recognized by protective antibodies not defined\", \"Contribution of EBA181 antibodies to clinical protection in vivo not established\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Characterized the RIII-V region as intrinsically disordered, informing how this part of the protein behaves structurally.\",\n      \"evidence\": \"Disorder prediction and atomic-resolution NMR of the recombinant EBA181 residue 945-1097 construct\",\n      \"pmids\": [\"25288451\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Functional role of the disordered RIII-V region during invasion not defined\", \"Whether disorder mediates partner interactions untested\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Revealed that eba181 transcription is stochastically variable across single schizonts, implicating epigenetic regulation as a source of the expression variation underlying immune evasion.\",\n      \"evidence\": \"Single-cell RNA sequencing validated by quantitative RT-PCR and RNA-FISH\",\n      \"pmids\": [\"35637187\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"The specific epigenetic marks or regulators controlling eba181 not identified\", \"Direct link between transcriptional variation and invasion phenotype not tested in this study\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Provided direct affinity measurements defining EBA181's molecular partners, including a physical Rh2b interaction that substantiates the earlier functional EBL/PfRh cooperation.\",\n      \"evidence\": \"Surface Plasmon Resonance of recombinant EBA181 against Neu5Ac/Neu5Gc sialic acids, Rh2b protein (KD ~3 µM), and erythrocyte membrane fractions\",\n      \"pmids\": [\"41198968\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Band 3 as the ~100 kDa erythrocyte receptor remains putative\", \"Single-method (SPR) measurements not independently confirmed\", \"Structural basis of the EBA181-Rh2b interaction unknown\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The definitive molecular identity of the erythrocyte surface receptor for EBA181 and the structural basis of its cooperation with PfRh2b remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No confirmed erythrocyte receptor identity (Band 3 still putative)\", \"No structure of an EBA181-receptor or EBA181-Rh2b complex\", \"Functional role of 4.1R binding and disordered RIII-V region in invasion undefined\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0030246\", \"supporting_discovery_ids\": [0, 10]},\n      {\"term_id\": \"GO:0050839\", \"supporting_discovery_ids\": [2, 3, 4, 10]},\n      {\"term_id\": \"GO:0008201\", \"supporting_discovery_ids\": [6]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0020009\", \"supporting_discovery_ids\": [0, 6]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0044409\", \"supporting_discovery_ids\": [0, 2, 5]},\n      {\"term_id\": \"GO:0006955\", \"supporting_discovery_ids\": [7]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"Erythrocyte membrane protein 4.1 (4.1R) 10 kDa domain [#3]\",\n      \"PfRh2a/b — functional cooperation [#5]\",\n      \"Rh2b merozoite protein — direct binding, KD ~3 µM [#10]\",\n      \"Neu5Ac / Neu5Gc sialic acids [#10]\",\n      \"~100 kDa erythrocyte membrane protein (Band 3 putative) [#10]\",\n      \"~53 kDa and ~33 kDa erythrocyte surface receptors [#2]\"\n    ],\n    \"other_free_text\": [\n      \"Region II is the erythrocyte-binding domain; polymorphisms alter binding level (later model) with binding level correlating with invasion function [#1, #4]\",\n      \"RIII-V region (residues 945-1097) is intrinsically disordered by NMR [#8]\",\n      \"Sialic acid-dependent, trypsin-resistant, chymotrypsin-sensitive binding phenotype; receptor distinct from glycophorin B [#0]\",\n      \"Gene disruptable in W2mef but not 3D7, indicating strain-dependent importance [#0]\",\n      \"Stochastic single-cell expression among schizonts consistent with epigenetic regulation [#9]\",\n      \"Target of naturally acquired invasion-inhibitory antibodies; expression variation aids immune evasion [#7]\"\n    ]\n  }\n}","audit_flag":null,"strains":[{"strain":"Pf3D7","gene_id":"PF3D7_0102500","name":null,"product":"erythrocyte binding antigen-181","uniprot_acc":null,"chromosome":null,"start_pos":null}],"gene_symbol":"EBA181","evaluation":null}