{"gene":"PF3D7_1219600","run_date":"2026-09-08T14:19:06","timeline":{"discoveries":[{"year":1995,"finding":"ATP2 (PfATPase2) is a P-type ATPase gene expressed during the intraerythrocytic life cycle of P. falciparum and appears to be required in the late stages of asexual development. Its full-length nucleotide and derived amino acid sequence were determined, and phylogenetic analysis showed it is remote from prokaryotic and mammalian P-type ATPases but shares features with a putative membrane-spanning Ca2+ ATPase involved in ribosome function in yeast.","method":"Molecular cloning, nucleotide sequencing, and phylogenetic analysis; expression analysis during intraerythrocytic stages","journal":"European journal of biochemistry","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, sequence-based characterization and expression analysis only, no biochemical functional assay","pmids":["7851389"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2021,"finding":"Recombinantly produced P. chabaudi ATP2 (PcATP2) associates with two Plasmodium-encoded Cdc50 proteins, PcCdc50B and PcCdc50A. The purified PcATP2/PcCdc50B complex displays ATPase activity stimulated by phosphatidylserine or phosphatidylethanolamine, and this activity is further upregulated by phosphatidylinositol 4-phosphate, demonstrating that ATP2 is a lipid-stimulated P4-ATPase (flippase).","method":"Recombinant protein expression, protein complex purification, in vitro ATPase activity assay with defined lipid substrates","journal":"Emerging microbes & infections","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro biochemical reconstitution of purified complex with direct ATPase activity measurements using defined lipid substrates; single lab but multiple orthogonal methods","pmids":["33372863"],"is_preprint":false,"attribution":[{"species":"Plasmodium chabaudi","strain":""}]},{"year":2022,"finding":"CDC50C is a binding partner of ATP2 in P. falciparum blood stages. Conditional disruption of CDC50C is essential for trophozoite maturation. The CDC50C-ATP2 complex influences parasite endocytosis of host cell hemoglobin and consequently hemozoin formation.","method":"Gene tagging, conditional gene disruption (DiCre-based), co-immunoprecipitation to identify CDC50C as ATP2 binding partner, phenotypic analysis of hemoglobin endocytosis and hemozoin formation","journal":"mBio","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal binding partner identification by co-IP plus conditional KO with specific cellular phenotype; single lab","pmids":["35862778"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2022,"finding":"Coarse-grained molecular dynamics simulations of PcATP2 (P. chabaudi ortholog of P. falciparum ATP2) embedded in a heterogeneous lipid membrane identified structural features of the lipid fingerprint of ATP2, including a potential phosphatidylinositol allosteric binding site and evolutionary conserved residues that may stabilize lipids in the binding pocket.","method":"Coarse-grained molecular dynamics (CG-MD) simulation","journal":"Membranes","confidence":"Low","confidence_rationale":"Tier 4 / Weak — computational prediction only, no experimental validation reported","pmids":["35877905"],"is_preprint":false,"attribution":[{"species":"Plasmodium chabaudi","strain":""}]},{"year":2025,"finding":"In P. falciparum, ATP2 (PfATP2) localizes to the parasite plasma membrane surface and is important for parasite growth. Parasites engineered to overexpress PfATP2 show reduced sensitivity to compounds MMV665794, MMV007224, and MMV665852, while PfATP2 knockdown renders parasites hypersensitive to the same compounds. PfATP2 overexpression increases the rate of internalization of a fluorescent phosphatidylserine analogue (NBD-PS), and knockdown reduces NBD-PS uptake, consistent with PfATP2 functioning as a major ATP-dependent phosphatidylserine internalisation (flipping) mechanism on the parasite plasma membrane. PfATP2 expression level does not affect cytosolic pH or the ability of these compounds to dysregulate parasite pH.","method":"Fluorescence microscopy for localization; conditional overexpression and knockdown (inducible systems); drug sensitivity assays; fluorescent lipid analogue (NBD-PS) uptake assay; cytosolic pH measurement","journal":"PLoS pathogens","confidence":"High","confidence_rationale":"Tier 2 / Strong — direct subcellular localization with functional consequence, reciprocal gain- and loss-of-function with specific lipid flipping readout, multiple orthogonal methods in single study","pmids":["41144577"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2025,"finding":"In vitro resistance selection in P. falciparum with compound 22 (a quinoxaline-based antimalarial) yielded copy number amplification of pfatp2, implicating ATP2 as a potential drug target or resistance determinant. Pre-existing P. falciparum lines with pfatp2 copy number variations showed reduced susceptibility to compound 22 and related analogues.","method":"In vitro evolution/resistance selection, whole-genome sequencing, copy number variation analysis, drug susceptibility assays on lines with pre-existing pfatp2 amplification","journal":"PLoS pathogens","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vitro resistance evolution with genomic confirmation and validation using pre-existing amplified lines; indirect evidence for target engagement","pmids":["39899599"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":"3D7"}]}],"current_model":"PF3D7_1219600 (ATP2) is a P4-type ATPase (lipid flippase) that localizes to the plasma membrane of P. falciparum, forms an essential complex with the CDC50C chaperone that influences trophozoite maturation and hemoglobin endocytosis, catalyzes ATP-dependent phosphatidylserine internalization (flipping) at the parasite surface, exhibits lipid-stimulated ATPase activity (activated by phosphatidylserine, phosphatidylethanolamine, and upregulated by phosphatidylinositol 4-phosphate) when partnered with a Cdc50 subunit, and its expression level modulates parasite sensitivity to several antimalarial compounds."},"narrative":{"mechanistic_narrative":"PF3D7_1219600 (ATP2) is a P-type ATPase of P. falciparum expressed during the intraerythrocytic cycle and required in the late stages of asexual development [PMID:7851389]. Biochemical reconstitution of the P. chabaudi ortholog establishes ATP2 as a lipid-stimulated P4-ATPase (flippase): purified in complex with a Plasmodium Cdc50 subunit, its ATPase activity is stimulated by phosphatidylserine or phosphatidylethanolamine and further upregulated by phosphatidylinositol 4-phosphate [PMID:33372863]. In P. falciparum blood stages ATP2 localizes to the parasite plasma membrane and drives ATP-dependent internalization of a phosphatidylserine analogue (NBD-PS), with overexpression increasing and knockdown reducing uptake — defining ATP2 as a major phosphatidylserine flipping mechanism at the parasite surface [PMID:41144577]. ATP2 associates with the chaperone CDC50C, whose conditional disruption is essential for trophozoite maturation, and the CDC50C–ATP2 complex influences endocytosis of host hemoglobin and hemozoin formation [PMID:35862778]. ATP2 expression level modulates parasite sensitivity to several antimalarial compounds, and its copy number amplification is selected under drug pressure, marking it as a candidate drug target or resistance determinant [PMID:41144577, PMID:39899599].","teleology":[{"year":1995,"claim":"Established that ATP2 is a distinct P-type ATPase gene expressed in blood-stage parasites, providing the first sequence-level identification and a hint of a late-stage asexual requirement.","evidence":"Molecular cloning, sequencing, and phylogenetic/expression analysis in P. falciparum","pmids":["7851389"],"confidence":"Low","gaps":["No biochemical activity assay to define substrate or transport function","Late-stage requirement inferred from expression, not from genetic perturbation"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2021,"claim":"Resolved the biochemical identity of ATP2 as a lipid-stimulated P4-ATPase requiring a Cdc50 partner, moving it from a predicted ATPase to a functionally defined flippase.","evidence":"Recombinant expression and purification of the PcATP2/PcCdc50B complex with in vitro ATPase assays using defined lipids (P. chabaudi)","pmids":["33372863"],"confidence":"High","gaps":["Direct demonstration of lipid translocation (as opposed to lipid-stimulated ATP hydrolysis) not shown in this system","Performed on the P. chabaudi ortholog, not P. falciparum ATP2"],"attribution":[{"species":"Plasmodium chabaudi","strain":""}]},{"year":2022,"claim":"Identified CDC50C as the P. falciparum ATP2 binding partner and linked the complex to trophozoite maturation and hemoglobin endocytosis, connecting flippase activity to a specific cellular process.","evidence":"Co-immunoprecipitation and DiCre conditional disruption with phenotypic analysis of hemoglobin endocytosis and hemozoin formation in P. falciparum","pmids":["35862778"],"confidence":"Medium","gaps":["Essentiality shown for CDC50C disruption; direct ATP2 loss-of-function phenotype not established here","Mechanistic link between lipid flipping and endocytosis not resolved"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2022,"claim":"Proposed structural determinants of ATP2 lipid recognition, including a candidate phosphatidylinositol allosteric site consistent with the PI4P stimulation seen biochemically.","evidence":"Coarse-grained molecular dynamics simulation of PcATP2 in a heterogeneous membrane (P. chabaudi ortholog)","pmids":["35877905"],"confidence":"Low","gaps":["Computational prediction with no experimental validation of the proposed binding site or residues","Based on the P. chabaudi ortholog"],"attribution":[{"species":"Plasmodium chabaudi","strain":""}]},{"year":2025,"claim":"Demonstrated in P. falciparum that ATP2 sits at the plasma membrane and functions as a major phosphatidylserine internalization mechanism, and that its expression level tunes sensitivity to specific antimalarial compounds independently of parasite pH.","evidence":"Fluorescence localization, reciprocal overexpression/knockdown, NBD-PS uptake assays, drug sensitivity and cytosolic pH measurements in P. falciparum","pmids":["41144577"],"confidence":"High","gaps":["Whether the tested compounds directly inhibit ATP2 catalysis versus acting through an ATP2-dependent pathway is not resolved","Directionality and full lipid substrate range at the P. falciparum surface not exhaustively defined"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2025,"claim":"Genetic evidence from resistance selection implicated ATP2 as a drug target or resistance determinant, reinforcing its therapeutic relevance.","evidence":"In vitro resistance evolution with compound 22, whole-genome sequencing, copy-number analysis, and validation with pre-existing pfatp2-amplified lines in P. falciparum 3D7","pmids":["39899599"],"confidence":"Medium","gaps":["Copy number amplification is indirect evidence for target engagement; direct binding/inhibition not shown","Whether amplification confers resistance through overexpression alone is not fully dissected"],"attribution":[{"species":"Plasmodium falciparum","strain":"3D7"}]},{"year":null,"claim":"How ATP2-mediated phosphatidylserine flipping mechanistically drives hemoglobin endocytosis and trophozoite maturation, and whether antimalarial compounds engage ATP2 directly, remain open.","evidence":"","pmids":[],"confidence":"Low","gaps":["No structural model validated experimentally for P. falciparum ATP2","Causal link between flippase activity and endocytosis unestablished","Direct compound–ATP2 binding not demonstrated"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]}],"mechanism_profile":{"molecular_activity":[],"localization":[],"pathway":[],"complexes":["ATP2–CDC50C complex (P. falciparum)","PcATP2–PcCdc50B / PcATP2–PcCdc50A complex (P. chabaudi)"],"partners":["CDC50C (P. FALCIPARUM)","PCCDC50B (P. CHABAUDI)","PCCDC50A (P. CHABAUDI)"],"other_free_text":["ATPase activity stimulated by phosphatidylserine and phosphatidylethanolamine, further upregulated by phosphatidylinositol 4-phosphate (P. chabaudi ortholog) [#1]","Expression level modulates parasite sensitivity to antimalarial compounds MMV665794, MMV007224, MMV665852 without affecting cytosolic pH [#4]","pfatp2 copy number amplification selected under compound 22 drug pressure; implicated as drug target/resistance determinant [#5]","CG-MD-predicted phosphatidylinositol allosteric binding site and conserved lipid-stabilizing residues (P. chabaudi ortholog, computational) [#3]"]}},"prefetch_data":{},"corpus_meta":[{"pmid":"7851389","id":"PMC_7851389","title":"Molecular cloning and sequence of two novel P-type adenosinetriphosphatases from Plasmodium falciparum.","date":"1995","source":"European journal of biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/7851389","citation_count":33,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["curated_ref"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"35862778","id":"PMC_35862778","title":"CDC50 Orthologues in Plasmodium falciparum Have Distinct Roles in Merozoite Egress and Trophozoite Maturation.","date":"2022","source":"mBio","url":"https://pubmed.ncbi.nlm.nih.gov/35862778","citation_count":16,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["ATP2"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"33372863","id":"PMC_33372863","title":"ATP2, The essential P4-ATPase of malaria parasites, catalyzes lipid-stimulated ATP hydrolysis in complex with a Cdc50 β-subunit.","date":"2021","source":"Emerging microbes & infections","url":"https://pubmed.ncbi.nlm.nih.gov/33372863","citation_count":13,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["ATP2","PfATP2","PcATP2"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"35877905","id":"PMC_35877905","title":"In Silico Assessment of the Lipid Fingerprint Signature of ATP2, the Essential P4-ATPase of Malaria Parasites.","date":"2022","source":"Membranes","url":"https://pubmed.ncbi.nlm.nih.gov/35877905","citation_count":3,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["ATP2","PcATP2"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"39899599","id":"PMC_39899599","title":"Quinoxaline-based anti-schistosomal compounds have potent anti-plasmodial activity.","date":"2025","source":"PLoS pathogens","url":"https://pubmed.ncbi.nlm.nih.gov/39899599","citation_count":2,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["PfATP2"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"38712185","id":"PMC_38712185","title":"Quinoxaline-Based Anti-Schistosomal Compounds Have Potent Anti-Malarial Activity.","date":"2024","source":"bioRxiv : the preprint server for biology","url":"https://pubmed.ncbi.nlm.nih.gov/38712185","citation_count":1,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["PfATP2"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"41144577","id":"PMC_41144577","title":"PfATP2 is a flippase on the Plasmodium falciparum surface that is important for growth and influences parasite sensitivity to antiplasmodial compounds.","date":"2025","source":"PLoS pathogens","url":"https://pubmed.ncbi.nlm.nih.gov/41144577","citation_count":0,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["PfATP2"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":6471,"output_tokens":1938,"usd":0.024241,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":7169,"output_tokens":3086,"usd":0.056497,"stage2_stop_reason":"end_turn"},"total_usd":0.080738,"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\": 1995,\n      \"finding\": \"ATP2 (PfATPase2) is a P-type ATPase gene expressed during the intraerythrocytic life cycle of P. falciparum and appears to be required in the late stages of asexual development. Its full-length nucleotide and derived amino acid sequence were determined, and phylogenetic analysis showed it is remote from prokaryotic and mammalian P-type ATPases but shares features with a putative membrane-spanning Ca2+ ATPase involved in ribosome function in yeast.\",\n      \"method\": \"Molecular cloning, nucleotide sequencing, and phylogenetic analysis; expression analysis during intraerythrocytic stages\",\n      \"journal\": \"European journal of biochemistry\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, sequence-based characterization and expression analysis only, no biochemical functional assay\",\n      \"pmids\": [\"7851389\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Recombinantly produced P. chabaudi ATP2 (PcATP2) associates with two Plasmodium-encoded Cdc50 proteins, PcCdc50B and PcCdc50A. The purified PcATP2/PcCdc50B complex displays ATPase activity stimulated by phosphatidylserine or phosphatidylethanolamine, and this activity is further upregulated by phosphatidylinositol 4-phosphate, demonstrating that ATP2 is a lipid-stimulated P4-ATPase (flippase).\",\n      \"method\": \"Recombinant protein expression, protein complex purification, in vitro ATPase activity assay with defined lipid substrates\",\n      \"journal\": \"Emerging microbes & infections\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro biochemical reconstitution of purified complex with direct ATPase activity measurements using defined lipid substrates; single lab but multiple orthogonal methods\",\n      \"pmids\": [\"33372863\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium chabaudi\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"CDC50C is a binding partner of ATP2 in P. falciparum blood stages. Conditional disruption of CDC50C is essential for trophozoite maturation. The CDC50C-ATP2 complex influences parasite endocytosis of host cell hemoglobin and consequently hemozoin formation.\",\n      \"method\": \"Gene tagging, conditional gene disruption (DiCre-based), co-immunoprecipitation to identify CDC50C as ATP2 binding partner, phenotypic analysis of hemoglobin endocytosis and hemozoin formation\",\n      \"journal\": \"mBio\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal binding partner identification by co-IP plus conditional KO with specific cellular phenotype; single lab\",\n      \"pmids\": [\"35862778\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Coarse-grained molecular dynamics simulations of PcATP2 (P. chabaudi ortholog of P. falciparum ATP2) embedded in a heterogeneous lipid membrane identified structural features of the lipid fingerprint of ATP2, including a potential phosphatidylinositol allosteric binding site and evolutionary conserved residues that may stabilize lipids in the binding pocket.\",\n      \"method\": \"Coarse-grained molecular dynamics (CG-MD) simulation\",\n      \"journal\": \"Membranes\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 4 / Weak — computational prediction only, no experimental validation reported\",\n      \"pmids\": [\"35877905\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium chabaudi\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"In P. falciparum, ATP2 (PfATP2) localizes to the parasite plasma membrane surface and is important for parasite growth. Parasites engineered to overexpress PfATP2 show reduced sensitivity to compounds MMV665794, MMV007224, and MMV665852, while PfATP2 knockdown renders parasites hypersensitive to the same compounds. PfATP2 overexpression increases the rate of internalization of a fluorescent phosphatidylserine analogue (NBD-PS), and knockdown reduces NBD-PS uptake, consistent with PfATP2 functioning as a major ATP-dependent phosphatidylserine internalisation (flipping) mechanism on the parasite plasma membrane. PfATP2 expression level does not affect cytosolic pH or the ability of these compounds to dysregulate parasite pH.\",\n      \"method\": \"Fluorescence microscopy for localization; conditional overexpression and knockdown (inducible systems); drug sensitivity assays; fluorescent lipid analogue (NBD-PS) uptake assay; cytosolic pH measurement\",\n      \"journal\": \"PLoS pathogens\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — direct subcellular localization with functional consequence, reciprocal gain- and loss-of-function with specific lipid flipping readout, multiple orthogonal methods in single study\",\n      \"pmids\": [\"41144577\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"In vitro resistance selection in P. falciparum with compound 22 (a quinoxaline-based antimalarial) yielded copy number amplification of pfatp2, implicating ATP2 as a potential drug target or resistance determinant. Pre-existing P. falciparum lines with pfatp2 copy number variations showed reduced susceptibility to compound 22 and related analogues.\",\n      \"method\": \"In vitro evolution/resistance selection, whole-genome sequencing, copy number variation analysis, drug susceptibility assays on lines with pre-existing pfatp2 amplification\",\n      \"journal\": \"PLoS pathogens\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vitro resistance evolution with genomic confirmation and validation using pre-existing amplified lines; indirect evidence for target engagement\",\n      \"pmids\": [\"39899599\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"3D7\"}]\n    }\n  ],\n  \"current_model\": \"PF3D7_1219600 (ATP2) is a P4-type ATPase (lipid flippase) that localizes to the plasma membrane of P. falciparum, forms an essential complex with the CDC50C chaperone that influences trophozoite maturation and hemoglobin endocytosis, catalyzes ATP-dependent phosphatidylserine internalization (flipping) at the parasite surface, exhibits lipid-stimulated ATPase activity (activated by phosphatidylserine, phosphatidylethanolamine, and upregulated by phosphatidylinositol 4-phosphate) when partnered with a Cdc50 subunit, and its expression level modulates parasite sensitivity to several antimalarial compounds.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"PF3D7_1219600 (ATP2) is a P-type ATPase of P. falciparum expressed during the intraerythrocytic cycle and required in the late stages of asexual development [#0]. Biochemical reconstitution of the P. chabaudi ortholog establishes ATP2 as a lipid-stimulated P4-ATPase (flippase): purified in complex with a Plasmodium Cdc50 subunit, its ATPase activity is stimulated by phosphatidylserine or phosphatidylethanolamine and further upregulated by phosphatidylinositol 4-phosphate [#1]. In P. falciparum blood stages ATP2 localizes to the parasite plasma membrane and drives ATP-dependent internalization of a phosphatidylserine analogue (NBD-PS), with overexpression increasing and knockdown reducing uptake — defining ATP2 as a major phosphatidylserine flipping mechanism at the parasite surface [#4]. ATP2 associates with the chaperone CDC50C, whose conditional disruption is essential for trophozoite maturation, and the CDC50C–ATP2 complex influences endocytosis of host hemoglobin and hemozoin formation [#2]. ATP2 expression level modulates parasite sensitivity to several antimalarial compounds, and its copy number amplification is selected under drug pressure, marking it as a candidate drug target or resistance determinant [#4, #5].\"\n,\n  \"teleology\": [\n    {\n      \"year\": 1995,\n      \"claim\": \"Established that ATP2 is a distinct P-type ATPase gene expressed in blood-stage parasites, providing the first sequence-level identification and a hint of a late-stage asexual requirement.\",\n      \"evidence\": \"Molecular cloning, sequencing, and phylogenetic/expression analysis in P. falciparum\",\n      \"pmids\": [\"7851389\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No biochemical activity assay to define substrate or transport function\", \"Late-stage requirement inferred from expression, not from genetic perturbation\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Resolved the biochemical identity of ATP2 as a lipid-stimulated P4-ATPase requiring a Cdc50 partner, moving it from a predicted ATPase to a functionally defined flippase.\",\n      \"evidence\": \"Recombinant expression and purification of the PcATP2/PcCdc50B complex with in vitro ATPase assays using defined lipids (P. chabaudi)\",\n      \"pmids\": [\"33372863\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct demonstration of lipid translocation (as opposed to lipid-stimulated ATP hydrolysis) not shown in this system\", \"Performed on the P. chabaudi ortholog, not P. falciparum ATP2\"],\n      \"attribution\": [{\"species\": \"Plasmodium chabaudi\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Identified CDC50C as the P. falciparum ATP2 binding partner and linked the complex to trophozoite maturation and hemoglobin endocytosis, connecting flippase activity to a specific cellular process.\",\n      \"evidence\": \"Co-immunoprecipitation and DiCre conditional disruption with phenotypic analysis of hemoglobin endocytosis and hemozoin formation in P. falciparum\",\n      \"pmids\": [\"35862778\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Essentiality shown for CDC50C disruption; direct ATP2 loss-of-function phenotype not established here\", \"Mechanistic link between lipid flipping and endocytosis not resolved\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Proposed structural determinants of ATP2 lipid recognition, including a candidate phosphatidylinositol allosteric site consistent with the PI4P stimulation seen biochemically.\",\n      \"evidence\": \"Coarse-grained molecular dynamics simulation of PcATP2 in a heterogeneous membrane (P. chabaudi ortholog)\",\n      \"pmids\": [\"35877905\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Computational prediction with no experimental validation of the proposed binding site or residues\", \"Based on the P. chabaudi ortholog\"],\n      \"attribution\": [{\"species\": \"Plasmodium chabaudi\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Demonstrated in P. falciparum that ATP2 sits at the plasma membrane and functions as a major phosphatidylserine internalization mechanism, and that its expression level tunes sensitivity to specific antimalarial compounds independently of parasite pH.\",\n      \"evidence\": \"Fluorescence localization, reciprocal overexpression/knockdown, NBD-PS uptake assays, drug sensitivity and cytosolic pH measurements in P. falciparum\",\n      \"pmids\": [\"41144577\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether the tested compounds directly inhibit ATP2 catalysis versus acting through an ATP2-dependent pathway is not resolved\", \"Directionality and full lipid substrate range at the P. falciparum surface not exhaustively defined\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Genetic evidence from resistance selection implicated ATP2 as a drug target or resistance determinant, reinforcing its therapeutic relevance.\",\n      \"evidence\": \"In vitro resistance evolution with compound 22, whole-genome sequencing, copy-number analysis, and validation with pre-existing pfatp2-amplified lines in P. falciparum 3D7\",\n      \"pmids\": [\"39899599\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Copy number amplification is indirect evidence for target engagement; direct binding/inhibition not shown\", \"Whether amplification confers resistance through overexpression alone is not fully dissected\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"3D7\"}]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How ATP2-mediated phosphatidylserine flipping mechanistically drives hemoglobin endocytosis and trophozoite maturation, and whether antimalarial compounds engage ATP2 directly, remain open.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No structural model validated experimentally for P. falciparum ATP2\", \"Causal link between flippase activity and endocytosis unestablished\", \"Direct compound–ATP2 binding not demonstrated\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0004012\", \"supporting_discovery_ids\": [1, 4]},\n      {\"term_id\": \"GO:0016887\", \"supporting_discovery_ids\": [0, 1]},\n      {\"term_id\": \"GO:0140326\", \"supporting_discovery_ids\": [4]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0020039\", \"supporting_discovery_ids\": [4]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0045332\", \"supporting_discovery_ids\": [1, 4]},\n      {\"term_id\": \"GO:0006897\", \"supporting_discovery_ids\": [2]}\n    ],\n    \"complexes\": [\n      \"ATP2–CDC50C complex (P. falciparum)\",\n      \"PcATP2–PcCdc50B / PcATP2–PcCdc50A complex (P. chabaudi)\"\n    ],\n    \"partners\": [\n      \"CDC50C (P. falciparum)\",\n      \"PcCdc50B (P. chabaudi)\",\n      \"PcCdc50A (P. chabaudi)\"\n    ],\n    \"other_free_text\": [\n      \"ATPase activity stimulated by phosphatidylserine and phosphatidylethanolamine, further upregulated by phosphatidylinositol 4-phosphate (P. chabaudi ortholog) [#1]\",\n      \"Expression level modulates parasite sensitivity to antimalarial compounds MMV665794, MMV007224, MMV665852 without affecting cytosolic pH [#4]\",\n      \"pfatp2 copy number amplification selected under compound 22 drug pressure; implicated as drug target/resistance determinant [#5]\",\n      \"CG-MD-predicted phosphatidylinositol allosteric binding site and conserved lipid-stabilizing residues (P. chabaudi ortholog, computational) [#3]\"\n    ]\n  }\n}","audit_flag":null,"strains":[{"strain":"Pf3D7","gene_id":"PF3D7_1219600","name":null,"product":"phospholipid-transporting ATPase 2","uniprot_acc":null,"chromosome":null,"start_pos":null},{"strain":"PbANKA","gene_id":"PBANKA_1434800","name":null,"product":"phospholipid-transporting ATPase 2, putative","uniprot_acc":null,"chromosome":null,"start_pos":null},{"strain":"PkH","gene_id":"PKNH_1438800","name":null,"product":"phospholipid-transporting ATPase 2, putative","uniprot_acc":null,"chromosome":null,"start_pos":null}],"gene_symbol":"ATP2","evaluation":null}