{"gene":"PF3D7_1034700","run_date":"2026-09-08T12:51:28","timeline":{"discoveries":[{"year":1996,"finding":"P. falciparum ARF1 (PfARF1, encoded by P. falciparum arf1) was expressed recombinantly in E. coli and purified with stoichiometric amounts of bound GDP. The recombinant protein stimulated cholera-toxin-catalyzed ADP-ribosyltransferase activity in a reaction dependent on dimyristoylglycerophosphocholine and cholate, and bound GTP with first-order kinetics (apparent rate constant k' = 0.0145 min-1). No intrinsic GTPase activity was detected. These results classify PfARF1 as a class I ARF family member.","method":"Recombinant protein expression in E. coli, GDP binding assay, GTP binding kinetics assay, cholera-toxin ADP-ribosyltransferase stimulation assay","journal":"European journal of biochemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro biochemical reconstitution with multiple orthogonal assays (GDP binding, GTP binding kinetics, ADP-ribosyltransferase stimulation) in a single rigorous study","pmids":["8954160"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":1997,"finding":"An ARF gene was cloned and characterized from P. falciparum. The encoded protein was identified as an ADP-ribosylation factor.","method":"Gene cloning, sequencing, and characterization","journal":"Molecular and biochemical parasitology","confidence":"Low","confidence_rationale":"Tier 3 / Weak — abstract not available for detailed method assessment; only title and citation metadata are present","pmids":["9247933"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":1997,"finding":"P. falciparum ARF and ARF-like genes were cloned and characterized, identifying multiple members of the ARF family in the parasite genome.","method":"Gene cloning and characterization","journal":"Molecular and biochemical parasitology","confidence":"Low","confidence_rationale":"Tier 3 / Weak — abstract not available; cannot assess specific mechanistic findings for PF3D7_1034700 versus other family members","pmids":["9084044"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2009,"finding":"Recombinant P. falciparum ARF1 (PfARF1) activates a unique bifunctional PIP5K (phosphatidylinositol 4-phosphate 5-kinase) in vitro, whereas phosphatidic acid does not, placing PfARF1 upstream of PtdIns(4,5)P2 synthesis in the parasite's phosphoinositide signalling pathway.","method":"In vitro kinase activation assay with recombinant ARF1 and recombinant PIP5K","journal":"International journal for parasitology","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — in vitro reconstitution assay demonstrating ARF1-dependent PIP5K activation, single lab, single method","pmids":["19171150"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2010,"finding":"The crystal structure of P. falciparum ARF1 (PfARF1) GTPase was determined in the GDP-bound conformation at 2.5 Å resolution, revealing structural similarities to mammalian class I ARF1 proteins.","method":"X-ray crystallography","journal":"Acta crystallographica. Section F, Structural biology and crystallization communications","confidence":"High","confidence_rationale":"Tier 1 / Moderate — atomic-resolution crystal structure at 2.5 Å with GDP-bound state characterized; single study but Tier 1 method","pmids":["21045287"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2015,"finding":"PfARF1 (N-myristoylated) co-localizes with a Golgi marker in P. falciparum blood-stage parasites. A chimeric protein combining the N-terminus of PfARF1 with additional motifs (putative palmitoylation site and lysine cluster) from PfAK2 was targeted to the parasite plasma membrane (PPM) but not translocated into the parasitophorous vacuole, demonstrating that PfARF1's N-terminus alone directs Golgi localization and that additional sequence features are required for PPM targeting and translocation.","method":"GFP-tagging, fluorescence microscopy, chimeric protein analysis, subcellular fractionation","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct localization by fluorescence microscopy with GFP fusions and chimeric protein dissection, two orthogonal approaches, single lab","pmids":["25909331"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2021,"finding":"PfARF1 (PF3D7_1034700) was isolated by co-immunoprecipitation with PfRab5b and identified by mass spectrometry. PfARF1 co-localizes with PfRab5b and PfRab1b adjacent to the ER in the early erythrocytic stage, but super-resolution microscopy showed PfARF1 and PfRab1b occupy different ER subdomains. Expression of an active or inactive PfARF1 mutant specifically inhibited trafficking of N-myristoylated adenylate kinase 2 (PfAK2) to the parasitophorous vacuole membrane, while export of the PEXEL-positive protein Rifin was also decreased by the inactive PfARF1 mutant. These data place PfARF1 as a regulator of ER exit for both PfAK2 (PEXEL-negative) and Rifin (PEXEL-positive) in P. falciparum.","method":"Co-immunoprecipitation, mass spectrometry, immunofluorescence microscopy, super-resolution microscopy, active/inactive mutant overexpression with trafficking readout","journal":"Frontiers in cellular and infection microbiology","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP with MS identification, direct localization by super-resolution microscopy, and genetic gain/loss-of-function with defined trafficking phenotype; multiple orthogonal methods in one study","pmids":["33604307"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]}],"current_model":"P. falciparum ARF1 (PF3D7_1034700) is a GDP/GTP-binding small GTPase of the class I ARF family that localizes to the Golgi/ER region in blood-stage parasites; it is activated by GTP loading, associates with PfRab5b at distinct ER subdomains, and functions as a regulator of vesicular export from the ER—directing PEXEL-negative PfAK2 into the parasitophorous vacuole pathway and contributing to PEXEL-positive Rifin export—while also serving as an upstream activator of the parasite's unique PIP5K to promote PtdIns(4,5)P2 synthesis."},"narrative":{"mechanistic_narrative":"PF3D7_1034700 encodes a class I ADP-ribosylation factor (PfARF1) that functions as a GDP/GTP-binding small GTPase regulating vesicular export from the endoplasmic reticulum in blood-stage Plasmodium falciparum [PMID:8954160, PMID:33604307]. In vitro, recombinant PfARF1 is purified with bound GDP, binds GTP with first-order kinetics, lacks detectable intrinsic GTPase activity, and stimulates cholera-toxin-catalyzed ADP-ribosyltransferase activity, defining it as a class I ARF family member [PMID:8954160]; its GDP-bound conformation was resolved crystallographically at 2.5 Å and resembles mammalian class I ARF1 [PMID:21045287]. N-myristoylated PfARF1 localizes to the Golgi via its N-terminus, and its N-terminus alone is insufficient for parasite-plasma-membrane targeting or translocation into the parasitophorous vacuole [PMID:25909331]. PfARF1 associates with PfRab5b and occupies ER subdomains distinct from PfRab1b, and both active and inactive PfARF1 mutants perturb ER exit, blocking trafficking of the PEXEL-negative PfAK2 to the parasitophorous vacuole membrane and reducing export of the PEXEL-positive protein Rifin [PMID:33604307]. Biochemically, recombinant PfARF1 acts upstream of phosphoinositide signalling by activating the parasite's unique bifunctional PIP5K to promote PtdIns(4,5)P2 synthesis [PMID:19171150].","teleology":[{"year":1996,"claim":"Establishing whether the P. falciparum ARF gene product is a functional nucleotide-binding factor was the first step to assigning it to the ARF family; biochemical reconstitution defined its enzymatic behavior.","evidence":"recombinant expression in E. coli with GDP-binding, GTP-binding kinetics, and cholera-toxin ADP-ribosyltransferase stimulation assays","pmids":["8954160"],"confidence":"High","gaps":["No intrinsic GTPase activity detected, leaving the GAP/GEF machinery that cycles PfARF1 in vivo unidentified","In vitro classification does not establish cellular function or localization"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":1997,"claim":"Cloning of ARF and ARF-like genes established the composition of the parasite ARF family, providing the sequence framework in which PF3D7_1034700 is a distinct member.","evidence":"gene cloning, sequencing, and characterization of P. falciparum ARF/ARF-like genes","pmids":["9247933","9084044"],"confidence":"Low","gaps":["Abstracts unavailable; specific attribution to PF3D7_1034700 versus sibling family members cannot be resolved","No functional data beyond sequence identification"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2009,"claim":"Whether PfARF1 links to phosphoinositide signalling was unknown; reconstitution placed it upstream of PtdIns(4,5)P2 synthesis.","evidence":"in vitro kinase activation assay with recombinant ARF1 and recombinant bifunctional PIP5K","pmids":["19171150"],"confidence":"Medium","gaps":["Single lab, single in vitro method; the interaction has not been validated in the cellular context","Physiological consequence of PIP5K activation for parasite trafficking not established"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2010,"claim":"The structural basis of PfARF1 nucleotide binding was undefined; a crystal structure resolved the GDP-bound conformation and confirmed class I ARF architecture.","evidence":"X-ray crystallography at 2.5 Å of the GDP-bound state","pmids":["21045287"],"confidence":"High","gaps":["Only the GDP-bound (inactive) state was captured; the GTP-bound active conformation and any parasite-specific interaction surfaces remain unresolved"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2015,"claim":"Where PfARF1 acts in the parasite and what dictates its targeting was open; localization and chimera dissection assigned it to the Golgi and mapped targeting determinants to the N-terminus.","evidence":"GFP-tagging, fluorescence microscopy, chimeric protein analysis, and subcellular fractionation in blood-stage parasites","pmids":["25909331"],"confidence":"Medium","gaps":["N-terminus alone directs Golgi localization but is insufficient for plasma-membrane targeting/translocation; the additional recruitment machinery is not identified","Single lab, overexpression-based readout"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2021,"claim":"The cargo and partners of PfARF1 in ER export were unknown; interaction mapping and mutant trafficking assays placed it as a regulator of ER exit for both PEXEL-negative and PEXEL-positive cargo.","evidence":"reciprocal Co-IP with mass spectrometry, super-resolution microscopy, and active/inactive mutant overexpression with PfAK2 and Rifin trafficking readouts","pmids":["33604307"],"confidence":"High","gaps":["Mechanism by which PfARF1 discriminates or acts on PEXEL-positive versus PEXEL-negative cargo is unresolved","Functional relationship between the PfRab5b association and the trafficking phenotype not dissected","Dominant-mutant overexpression does not establish endogenous requirement"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":null,"claim":"The nucleotide-cycling machinery (GEFs/GAPs), the physiological coupling between PfARF1-driven PIP5K activation and its ER-export function, and its endogenous requirement in the parasite life cycle remain unestablished.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No PfARF1 GEF or GAP identified","In vitro PIP5K activation and in-cell ER-export roles have not been integrated into one mechanistic pathway","No loss-of-function/knockout phenotype for endogenous PfARF1 reported in the corpus"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]}],"mechanism_profile":{"molecular_activity":[],"localization":[],"pathway":[],"complexes":[],"partners":["PFRAB5B","PFRAB1B","PIP5K","PFAK2"],"other_free_text":["Class I ADP-ribosylation factor; GDP-bound crystal structure resolves at 2.5 Å resembling mammalian ARF1 [#4].","N-terminal myristoylation directs Golgi localization; additional PfAK2-derived motifs are required for plasma-membrane targeting [#5].","Both active and inactive PfARF1 mutants impair ER exit of PEXEL-negative PfAK2 and reduce PEXEL-positive Rifin export [#6]."]}},"prefetch_data":{},"corpus_meta":[{"pmid":"10681568","id":"PMC_10681568","title":"Acetyl-CoA synthetase from the amitochondriate eukaryote Giardia lamblia belongs to the newly recognized superfamily of acyl-CoA synthetases (Nucleoside diphosphate-forming).","date":"2000","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/10681568","citation_count":95,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["ADP"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"17827348","id":"PMC_17827348","title":"Plasmodium falciparum Sir2: an unusual sirtuin with dual histone deacetylase and ADP-ribosyltransferase activity.","date":"2007","source":"Eukaryotic cell","url":"https://pubmed.ncbi.nlm.nih.gov/17827348","citation_count":81,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["ADP"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"18729382","id":"PMC_18729382","title":"Plasmodium falciparum Sir2 is an NAD+-dependent deacetylase and an acetyllysine-dependent and acetyllysine-independent NAD+ glycohydrolase.","date":"2008","source":"Biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/18729382","citation_count":41,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["ADP"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"8954160","id":"PMC_8954160","title":"Isolation, expression and characterization of the gene for an ADP-ribosylation factor from the human malaria parasite, Plasmodium falciparum.","date":"1996","source":"European journal of biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/8954160","citation_count":40,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["ADP-ribosylation factor","ADP"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"19171150","id":"PMC_19171150","title":"A unique phosphatidylinositol 4-phosphate 5-kinase is activated by ADP-ribosylation factor in Plasmodium falciparum.","date":"2009","source":"International journal for parasitology","url":"https://pubmed.ncbi.nlm.nih.gov/19171150","citation_count":36,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["ADP-ribosylation factor","ADP"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"25909331","id":"PMC_25909331","title":"Alternative Protein Secretion in the Malaria Parasite Plasmodium falciparum.","date":"2015","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/25909331","citation_count":23,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["ADP-ribosylation factor","ADP"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"11555294","id":"PMC_11555294","title":"A point mutation in an unusual Sec7 domain is linked to brefeldin A resistance in a Plasmodium falciparum line generated by drug selection.","date":"2001","source":"Molecular microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/11555294","citation_count":21,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["ADP"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"6307262","id":"PMC_6307262","title":"ADP-ribosyltransferase in Plasmodium (malaria parasites).","date":"1983","source":"The Biochemical journal","url":"https://pubmed.ncbi.nlm.nih.gov/6307262","citation_count":16,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["ADP"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"23607486","id":"PMC_23607486","title":"Temporal evaluation of commitment to sexual development in Plasmodium falciparum.","date":"2013","source":"Malaria journal","url":"https://pubmed.ncbi.nlm.nih.gov/23607486","citation_count":14,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["ADP"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"9247933","id":"PMC_9247933","title":"Identification and characterization of an ADP-ribosylation factor in Plasmodium falciparum.","date":"1997","source":"Molecular and biochemical parasitology","url":"https://pubmed.ncbi.nlm.nih.gov/9247933","citation_count":10,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["ADP-ribosylation factor","ADP"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"9084044","id":"PMC_9084044","title":"Cloning and characterization of Plasmodium falciparum ADP-ribosylation factor and factor-like genes.","date":"1997","source":"Molecular and biochemical parasitology","url":"https://pubmed.ncbi.nlm.nih.gov/9084044","citation_count":10,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["ADP-ribosylation factor","ADP"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"21045287","id":"PMC_21045287","title":"Structure of Plasmodium falciparum ADP-ribosylation factor 1.","date":"2010","source":"Acta crystallographica. Section F, Structural biology and crystallization communications","url":"https://pubmed.ncbi.nlm.nih.gov/21045287","citation_count":8,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["ADP-ribosylation factor","ADP"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"15500915","id":"PMC_15500915","title":"Double cross-over gene replacement within the sec 7 domain of a GDP-GTP exchange factor from Plasmodium falciparum allows the generation of a transgenic brefeldin A-resistant parasite line.","date":"2004","source":"Molecular and biochemical parasitology","url":"https://pubmed.ncbi.nlm.nih.gov/15500915","citation_count":8,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["ADP-ribosylation factor","ADP"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"38349168","id":"PMC_38349168","title":"Toxoplasma and Plasmodium associate with host Arfs during infection.","date":"2024","source":"mSphere","url":"https://pubmed.ncbi.nlm.nih.gov/38349168","citation_count":1,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["ADP"],"competing_organism_flag":true,"competing_organism_match":"Toxoplasma","competing_organism_only":true},{"pmid":"33604307","id":"PMC_33604307","title":"Rab5b-Associated Arf1 GTPase Regulates Export of N-Myristoylated Adenylate Kinase 2 From the Endoplasmic Reticulum in Plasmodium falciparum.","date":"2021","source":"Frontiers in cellular and infection microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/33604307","citation_count":7,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["curated_ref"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"22102228","id":"PMC_22102228","title":"Structure of the catalytic domain of Plasmodium falciparum ARF GTPase-activating protein (ARFGAP).","date":"2011","source":"Acta crystallographica. Section F, Structural biology and crystallization communications","url":"https://pubmed.ncbi.nlm.nih.gov/22102228","citation_count":2,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["ADP-ribosylation factor","ADP"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":10082,"output_tokens":2144,"usd":0.031203,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":7290,"output_tokens":2973,"usd":0.055387,"stage2_stop_reason":"end_turn"},"total_usd":0.08659,"stage1_batch_id":"msgbatch_01DisAaTypwmC8QwdMBuePHo","stage2_batch_id":"msgbatch_0184zxZTqxiEfdYYfPMfkqjb","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1996,\n      \"finding\": \"P. falciparum ARF1 (PfARF1, encoded by P. falciparum arf1) was expressed recombinantly in E. coli and purified with stoichiometric amounts of bound GDP. The recombinant protein stimulated cholera-toxin-catalyzed ADP-ribosyltransferase activity in a reaction dependent on dimyristoylglycerophosphocholine and cholate, and bound GTP with first-order kinetics (apparent rate constant k' = 0.0145 min-1). No intrinsic GTPase activity was detected. These results classify PfARF1 as a class I ARF family member.\",\n      \"method\": \"Recombinant protein expression in E. coli, GDP binding assay, GTP binding kinetics assay, cholera-toxin ADP-ribosyltransferase stimulation assay\",\n      \"journal\": \"European journal of biochemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro biochemical reconstitution with multiple orthogonal assays (GDP binding, GTP binding kinetics, ADP-ribosyltransferase stimulation) in a single rigorous study\",\n      \"pmids\": [\"8954160\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"An ARF gene was cloned and characterized from P. falciparum. The encoded protein was identified as an ADP-ribosylation factor.\",\n      \"method\": \"Gene cloning, sequencing, and characterization\",\n      \"journal\": \"Molecular and biochemical parasitology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — abstract not available for detailed method assessment; only title and citation metadata are present\",\n      \"pmids\": [\"9247933\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"P. falciparum ARF and ARF-like genes were cloned and characterized, identifying multiple members of the ARF family in the parasite genome.\",\n      \"method\": \"Gene cloning and characterization\",\n      \"journal\": \"Molecular and biochemical parasitology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — abstract not available; cannot assess specific mechanistic findings for PF3D7_1034700 versus other family members\",\n      \"pmids\": [\"9084044\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Recombinant P. falciparum ARF1 (PfARF1) activates a unique bifunctional PIP5K (phosphatidylinositol 4-phosphate 5-kinase) in vitro, whereas phosphatidic acid does not, placing PfARF1 upstream of PtdIns(4,5)P2 synthesis in the parasite's phosphoinositide signalling pathway.\",\n      \"method\": \"In vitro kinase activation assay with recombinant ARF1 and recombinant PIP5K\",\n      \"journal\": \"International journal for parasitology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — in vitro reconstitution assay demonstrating ARF1-dependent PIP5K activation, single lab, single method\",\n      \"pmids\": [\"19171150\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"The crystal structure of P. falciparum ARF1 (PfARF1) GTPase was determined in the GDP-bound conformation at 2.5 Å resolution, revealing structural similarities to mammalian class I ARF1 proteins.\",\n      \"method\": \"X-ray crystallography\",\n      \"journal\": \"Acta crystallographica. Section F, Structural biology and crystallization communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — atomic-resolution crystal structure at 2.5 Å with GDP-bound state characterized; single study but Tier 1 method\",\n      \"pmids\": [\"21045287\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"PfARF1 (N-myristoylated) co-localizes with a Golgi marker in P. falciparum blood-stage parasites. A chimeric protein combining the N-terminus of PfARF1 with additional motifs (putative palmitoylation site and lysine cluster) from PfAK2 was targeted to the parasite plasma membrane (PPM) but not translocated into the parasitophorous vacuole, demonstrating that PfARF1's N-terminus alone directs Golgi localization and that additional sequence features are required for PPM targeting and translocation.\",\n      \"method\": \"GFP-tagging, fluorescence microscopy, chimeric protein analysis, subcellular fractionation\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct localization by fluorescence microscopy with GFP fusions and chimeric protein dissection, two orthogonal approaches, single lab\",\n      \"pmids\": [\"25909331\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"PfARF1 (PF3D7_1034700) was isolated by co-immunoprecipitation with PfRab5b and identified by mass spectrometry. PfARF1 co-localizes with PfRab5b and PfRab1b adjacent to the ER in the early erythrocytic stage, but super-resolution microscopy showed PfARF1 and PfRab1b occupy different ER subdomains. Expression of an active or inactive PfARF1 mutant specifically inhibited trafficking of N-myristoylated adenylate kinase 2 (PfAK2) to the parasitophorous vacuole membrane, while export of the PEXEL-positive protein Rifin was also decreased by the inactive PfARF1 mutant. These data place PfARF1 as a regulator of ER exit for both PfAK2 (PEXEL-negative) and Rifin (PEXEL-positive) in P. falciparum.\",\n      \"method\": \"Co-immunoprecipitation, mass spectrometry, immunofluorescence microscopy, super-resolution microscopy, active/inactive mutant overexpression with trafficking readout\",\n      \"journal\": \"Frontiers in cellular and infection microbiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP with MS identification, direct localization by super-resolution microscopy, and genetic gain/loss-of-function with defined trafficking phenotype; multiple orthogonal methods in one study\",\n      \"pmids\": [\"33604307\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    }\n  ],\n  \"current_model\": \"P. falciparum ARF1 (PF3D7_1034700) is a GDP/GTP-binding small GTPase of the class I ARF family that localizes to the Golgi/ER region in blood-stage parasites; it is activated by GTP loading, associates with PfRab5b at distinct ER subdomains, and functions as a regulator of vesicular export from the ER—directing PEXEL-negative PfAK2 into the parasitophorous vacuole pathway and contributing to PEXEL-positive Rifin export—while also serving as an upstream activator of the parasite's unique PIP5K to promote PtdIns(4,5)P2 synthesis.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"PF3D7_1034700 encodes a class I ADP-ribosylation factor (PfARF1) that functions as a GDP/GTP-binding small GTPase regulating vesicular export from the endoplasmic reticulum in blood-stage Plasmodium falciparum [#0, #6]. In vitro, recombinant PfARF1 is purified with bound GDP, binds GTP with first-order kinetics, lacks detectable intrinsic GTPase activity, and stimulates cholera-toxin-catalyzed ADP-ribosyltransferase activity, defining it as a class I ARF family member [#0]; its GDP-bound conformation was resolved crystallographically at 2.5 Å and resembles mammalian class I ARF1 [#4]. N-myristoylated PfARF1 localizes to the Golgi via its N-terminus, and its N-terminus alone is insufficient for parasite-plasma-membrane targeting or translocation into the parasitophorous vacuole [#5]. PfARF1 associates with PfRab5b and occupies ER subdomains distinct from PfRab1b, and both active and inactive PfARF1 mutants perturb ER exit, blocking trafficking of the PEXEL-negative PfAK2 to the parasitophorous vacuole membrane and reducing export of the PEXEL-positive protein Rifin [#6]. Biochemically, recombinant PfARF1 acts upstream of phosphoinositide signalling by activating the parasite's unique bifunctional PIP5K to promote PtdIns(4,5)P2 synthesis [#3].\",\n  \"teleology\": [\n    {\n      \"year\": 1996,\n      \"claim\": \"Establishing whether the P. falciparum ARF gene product is a functional nucleotide-binding factor was the first step to assigning it to the ARF family; biochemical reconstitution defined its enzymatic behavior.\",\n      \"evidence\": \"recombinant expression in E. coli with GDP-binding, GTP-binding kinetics, and cholera-toxin ADP-ribosyltransferase stimulation assays\",\n      \"pmids\": [\"8954160\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No intrinsic GTPase activity detected, leaving the GAP/GEF machinery that cycles PfARF1 in vivo unidentified\", \"In vitro classification does not establish cellular function or localization\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 1997,\n      \"claim\": \"Cloning of ARF and ARF-like genes established the composition of the parasite ARF family, providing the sequence framework in which PF3D7_1034700 is a distinct member.\",\n      \"evidence\": \"gene cloning, sequencing, and characterization of P. falciparum ARF/ARF-like genes\",\n      \"pmids\": [\"9247933\", \"9084044\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Abstracts unavailable; specific attribution to PF3D7_1034700 versus sibling family members cannot be resolved\", \"No functional data beyond sequence identification\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Whether PfARF1 links to phosphoinositide signalling was unknown; reconstitution placed it upstream of PtdIns(4,5)P2 synthesis.\",\n      \"evidence\": \"in vitro kinase activation assay with recombinant ARF1 and recombinant bifunctional PIP5K\",\n      \"pmids\": [\"19171150\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab, single in vitro method; the interaction has not been validated in the cellular context\", \"Physiological consequence of PIP5K activation for parasite trafficking not established\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"The structural basis of PfARF1 nucleotide binding was undefined; a crystal structure resolved the GDP-bound conformation and confirmed class I ARF architecture.\",\n      \"evidence\": \"X-ray crystallography at 2.5 Å of the GDP-bound state\",\n      \"pmids\": [\"21045287\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Only the GDP-bound (inactive) state was captured; the GTP-bound active conformation and any parasite-specific interaction surfaces remain unresolved\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Where PfARF1 acts in the parasite and what dictates its targeting was open; localization and chimera dissection assigned it to the Golgi and mapped targeting determinants to the N-terminus.\",\n      \"evidence\": \"GFP-tagging, fluorescence microscopy, chimeric protein analysis, and subcellular fractionation in blood-stage parasites\",\n      \"pmids\": [\"25909331\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"N-terminus alone directs Golgi localization but is insufficient for plasma-membrane targeting/translocation; the additional recruitment machinery is not identified\", \"Single lab, overexpression-based readout\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"The cargo and partners of PfARF1 in ER export were unknown; interaction mapping and mutant trafficking assays placed it as a regulator of ER exit for both PEXEL-negative and PEXEL-positive cargo.\",\n      \"evidence\": \"reciprocal Co-IP with mass spectrometry, super-resolution microscopy, and active/inactive mutant overexpression with PfAK2 and Rifin trafficking readouts\",\n      \"pmids\": [\"33604307\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism by which PfARF1 discriminates or acts on PEXEL-positive versus PEXEL-negative cargo is unresolved\", \"Functional relationship between the PfRab5b association and the trafficking phenotype not dissected\", \"Dominant-mutant overexpression does not establish endogenous requirement\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The nucleotide-cycling machinery (GEFs/GAPs), the physiological coupling between PfARF1-driven PIP5K activation and its ER-export function, and its endogenous requirement in the parasite life cycle remain unestablished.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No PfARF1 GEF or GAP identified\", \"In vitro PIP5K activation and in-cell ER-export roles have not been integrated into one mechanistic pathway\", \"No loss-of-function/knockout phenotype for endogenous PfARF1 reported in the corpus\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0005525\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"GO:0019003\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"GO:0005096\", \"supporting_discovery_ids\": [3]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005794\", \"supporting_discovery_ids\": [5]},\n      {\"term_id\": \"GO:0005783\", \"supporting_discovery_ids\": [6]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0006886\", \"supporting_discovery_ids\": [6]},\n      {\"term_id\": \"GO:0046488\", \"supporting_discovery_ids\": [3]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"PfRab5b\", \"PfRab1b\", \"PIP5K\", \"PfAK2\"],\n    \"other_free_text\": [\n      \"Class I ADP-ribosylation factor; GDP-bound crystal structure resolves at 2.5 Å resembling mammalian ARF1 [#4].\",\n      \"N-terminal myristoylation directs Golgi localization; additional PfAK2-derived motifs are required for plasma-membrane targeting [#5].\",\n      \"Both active and inactive PfARF1 mutants impair ER exit of PEXEL-negative PfAK2 and reduce PEXEL-positive Rifin export [#6].\"\n    ]\n  }\n}","audit_flag":{"gene":"PF3D7_1034700","tier":"IDENTITY_CHECK","verdict":"identity unverified","subtype":"names_other_cards","uniprot_band":"","rules_fired":"R12","issue":"No cited paper names this card; 5 of 7 cited papers name other catalogue genes (PF3D7_1020900, PF3D7_0816900, PF3D7_0110600). The summary may describe one of those genes."},"strains":[{"strain":"Pf3D7","gene_id":"PF3D7_1034700","name":null,"product":"ADP-ribosylation factor, putative","uniprot_acc":null,"chromosome":null,"start_pos":null},{"strain":"PbANKA","gene_id":"PBANKA_0518500","name":null,"product":"ADP-ribosylation factor, putative","uniprot_acc":null,"chromosome":null,"start_pos":null},{"strain":"PkH","gene_id":"PKNH_0619900","name":null,"product":"ADP-ribosylation factor, putative","uniprot_acc":null,"chromosome":null,"start_pos":null}],"gene_symbol":"","evaluation":null}