{"gene":"PF3D7_0216400","run_date":"2026-09-07T10:55:51","timeline":{"discoveries":[{"year":2018,"finding":"Conditional inactivation of PfVPS45 in P. falciparum blood-stage parasites caused accumulation of host cell cytosol-filled vesicles within the parasite and blocked delivery of hemoglobin to the digestive (food) vacuole, arresting parasite growth. A proportion of these vesicle intermediates was positive for phosphatidylinositol 3-phosphate (PI3P), indicating endosomal characteristics. This identifies VPS45 as an essential factor in host cell cytosol uptake (HCCU) and endosomal transport to the digestive vacuole.","method":"Conditional inactivation (DiCre-based excision), fluorescence microscopy, vesicle accumulation phenotyping, PI3P marker co-localization","journal":"Cell host & microbe","confidence":"High","confidence_rationale":"Tier 2 / Strong — conditional genetic inactivation with specific cellular phenotype (vesicle accumulation, blocked hemoglobin delivery), PI3P marker localization, and arrested growth readout; replicated conceptually in subsequent independent work (PMID:38820535)","pmids":["30581113"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2020,"finding":"In P. falciparum, VPS45 is implicated in the biogenesis of the inner membrane complex (alveoli), likely acting in a coordinated manner with the SNARE proteins Stx16 and Stx6, in addition to its role in trafficking of endocytosed host proteins.","method":"Functional genetic analysis of SEC1/Munc18 and SNARE proteins in Toxoplasma gondii and Plasmodium falciparum; vesicular trafficking assays","journal":"mBio","confidence":"Medium","confidence_rationale":"Tier 3 / Weak — single study, functional inference from genetic perturbation of interacting SNARE partners; specific mechanistic details for PfVPS45 in IMC biogenesis are inferred rather than directly demonstrated by VPS45 loss-of-function in P. falciparum alone","pmids":["33082261"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2024,"finding":"PfVPS45 functions together with a parasite Rabenosyn-5-like protein (PfRbsn5L) and PfRab5b (but not PfRab5a) in endosomal transport of host cell cytosol (HCC) to the food vacuole. Inactivation of PfRbsn5L produced PI3P- and PfRab5b-decorated HCC-filled vesicles, phenotypically similar to loss of VPS45. Conditional double protein inactivation further established that the PfKelch13 compartment acts upstream of the Rbsn5L/VPS45/Rab5b-dependent endosomal route.","method":"Conditional inactivation (single and double), fluorescence microscopy, PI3P and Rab5b co-localization, conditional double protein inactivation epistasis system","journal":"PLoS biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — conditional genetic inactivation of multiple components with orthogonal PI3P/Rab5b marker readouts, epistasis established by double inactivation system; builds on and replicates prior VPS45 findings","pmids":["38820535"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]}],"current_model":"In P. falciparum blood-stage parasites, VPS45 (PF3D7_0216400) is an essential endosomal trafficking factor that acts together with Rabenosyn-5-like protein (PfRbsn5L) and PfRab5b — downstream of the PfKelch13 compartment at the parasite plasma membrane — to transport host cell cytosol-filled, PI3P-positive endosomal vesicles to the digestive (food) vacuole for hemoglobin degradation, and is additionally implicated in inner membrane complex biogenesis in coordination with SNARE proteins Stx16 and Stx6."},"narrative":{"mechanistic_narrative":"VPS45 (PF3D7_0216400) is an essential endosomal trafficking factor in P. falciparum blood-stage parasites that mediates the delivery of host cell cytosol to the digestive (food) vacuole for hemoglobin degradation [PMID:30581113]. Conditional inactivation of VPS45 blocks hemoglobin delivery and causes accumulation of host cell cytosol-filled vesicles, a proportion of which are decorated with phosphatidylinositol 3-phosphate (PI3P), marking them as endosomal intermediates, with a consequent arrest of parasite growth [PMID:30581113]. VPS45 acts within a defined endosomal route together with a parasite Rabenosyn-5-like protein (PfRbsn5L) and PfRab5b — but not PfRab5a — and epistasis analysis places this Rbsn5L/VPS45/Rab5b-dependent step downstream of the PfKelch13 compartment [PMID:38820535]. Beyond this host cell cytosol uptake pathway, VPS45 is additionally implicated in biogenesis of the inner membrane complex in coordination with the SNARE proteins Stx16 and Stx6 [PMID:33082261]. No structural or biochemical characterization of the VPS45 protein itself, or of its direct molecular interactions, has been established in the available corpus.","teleology":[{"year":2018,"claim":"Establishing whether VPS45 has a required role in blood-stage parasite biology, this work showed it is essential for delivering host cell cytosol to the digestive vacuole for hemoglobin degradation.","evidence":"DiCre-based conditional inactivation in P. falciparum with fluorescence microscopy, vesicle accumulation phenotyping, and PI3P marker co-localization","pmids":["30581113"],"confidence":"High","gaps":["Direct molecular partners of VPS45 mediating vesicle transport not identified","Biochemical/structural basis of VPS45 function not resolved","Whether VPS45 acts in vesicle formation, budding, or fusion not distinguished"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2020,"claim":"Extending VPS45 function beyond endocytic trafficking, this work implicated it in inner membrane complex (alveoli) biogenesis in coordination with SNARE proteins Stx16 and Stx6.","evidence":"Functional genetic analysis of SEC1/Munc18 and SNARE proteins in T. gondii and P. falciparum with vesicular trafficking assays","pmids":["33082261"],"confidence":"Medium","gaps":["IMC biogenesis role inferred from SNARE partner perturbation rather than direct VPS45 loss-of-function in this context","Direct interaction of VPS45 with Stx16/Stx6 not biochemically demonstrated","Mechanism linking VPS45 to alveolar membrane formation unresolved"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2024,"claim":"Defining the pathway context of VPS45, this work placed it in a discrete endosomal route with PfRbsn5L and PfRab5b acting downstream of the PfKelch13 compartment.","evidence":"Single and conditional double protein inactivation in P. falciparum with PI3P/Rab5b co-localization and epistasis analysis","pmids":["38820535"],"confidence":"High","gaps":["Direct physical interaction among VPS45, PfRbsn5L, and PfRab5b not shown biochemically","Specificity determinants selecting Rab5b over Rab5a unknown","Molecular link between the PfKelch13 compartment and the VPS45 step not defined"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":null,"claim":"The biochemical activity of VPS45, its direct binding partners, and its structural basis for coordinating endosomal transport remain undefined.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No direct protein-protein interaction data for VPS45 in the corpus","No structural model of VPS45 established","Whether the endosomal and IMC roles are mechanistically related is unknown"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]}],"mechanism_profile":{"molecular_activity":[],"localization":[],"pathway":[],"complexes":[],"partners":["PFRBSN5L (RABENOSYN-5-LIKE PROTEIN)","PFRAB5B","STX16","STX6"],"other_free_text":["Essential for P. falciparum blood-stage growth; conditional inactivation causes accumulation of PI3P-positive host cell cytosol-filled vesicles and blocks hemoglobin delivery to the food vacuole [#0]","Acts downstream of the PfKelch13 compartment in the Rbsn5L/VPS45/Rab5b endosomal route [#2]"]}},"prefetch_data":{},"corpus_meta":[{"pmid":"30581113","id":"PMC_30581113","title":"PfVPS45 Is Required for Host Cell Cytosol Uptake by Malaria Blood Stage Parasites.","date":"2018","source":"Cell host & microbe","url":"https://pubmed.ncbi.nlm.nih.gov/30581113","citation_count":62,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["VPS45","PfVPS45"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"33082261","id":"PMC_33082261","title":"The ZIP Code of Vesicle Trafficking in Apicomplexa: SEC1/Munc18 and SNARE Proteins.","date":"2020","source":"mBio","url":"https://pubmed.ncbi.nlm.nih.gov/33082261","citation_count":33,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["VPS45"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"38820535","id":"PMC_38820535","title":"Role of Rabenosyn-5 and Rab5b in host cell cytosol uptake reveals conservation of endosomal transport in malaria parasites.","date":"2024","source":"PLoS biology","url":"https://pubmed.ncbi.nlm.nih.gov/38820535","citation_count":12,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["VPS45","PfVPS45"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"31003757","id":"PMC_31003757","title":"Elucidating Host Cell Uptake by Malaria Parasites.","date":"2019","source":"Trends in parasitology","url":"https://pubmed.ncbi.nlm.nih.gov/31003757","citation_count":5,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["VPS45"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":4821,"output_tokens":1183,"usd":0.016104,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":5978,"output_tokens":2029,"usd":0.040308,"stage2_stop_reason":"end_turn"},"total_usd":0.056412,"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\": 2018,\n      \"finding\": \"Conditional inactivation of PfVPS45 in P. falciparum blood-stage parasites caused accumulation of host cell cytosol-filled vesicles within the parasite and blocked delivery of hemoglobin to the digestive (food) vacuole, arresting parasite growth. A proportion of these vesicle intermediates was positive for phosphatidylinositol 3-phosphate (PI3P), indicating endosomal characteristics. This identifies VPS45 as an essential factor in host cell cytosol uptake (HCCU) and endosomal transport to the digestive vacuole.\",\n      \"method\": \"Conditional inactivation (DiCre-based excision), fluorescence microscopy, vesicle accumulation phenotyping, PI3P marker co-localization\",\n      \"journal\": \"Cell host & microbe\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — conditional genetic inactivation with specific cellular phenotype (vesicle accumulation, blocked hemoglobin delivery), PI3P marker localization, and arrested growth readout; replicated conceptually in subsequent independent work (PMID:38820535)\",\n      \"pmids\": [\"30581113\"],\n      \"is_preprint\": false,\n      \"attribution\": [\n        {\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}\n      ]\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"In P. falciparum, VPS45 is implicated in the biogenesis of the inner membrane complex (alveoli), likely acting in a coordinated manner with the SNARE proteins Stx16 and Stx6, in addition to its role in trafficking of endocytosed host proteins.\",\n      \"method\": \"Functional genetic analysis of SEC1/Munc18 and SNARE proteins in Toxoplasma gondii and Plasmodium falciparum; vesicular trafficking assays\",\n      \"journal\": \"mBio\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single study, functional inference from genetic perturbation of interacting SNARE partners; specific mechanistic details for PfVPS45 in IMC biogenesis are inferred rather than directly demonstrated by VPS45 loss-of-function in P. falciparum alone\",\n      \"pmids\": [\"33082261\"],\n      \"is_preprint\": false,\n      \"attribution\": [\n        {\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}\n      ]\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"PfVPS45 functions together with a parasite Rabenosyn-5-like protein (PfRbsn5L) and PfRab5b (but not PfRab5a) in endosomal transport of host cell cytosol (HCC) to the food vacuole. Inactivation of PfRbsn5L produced PI3P- and PfRab5b-decorated HCC-filled vesicles, phenotypically similar to loss of VPS45. Conditional double protein inactivation further established that the PfKelch13 compartment acts upstream of the Rbsn5L/VPS45/Rab5b-dependent endosomal route.\",\n      \"method\": \"Conditional inactivation (single and double), fluorescence microscopy, PI3P and Rab5b co-localization, conditional double protein inactivation epistasis system\",\n      \"journal\": \"PLoS biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — conditional genetic inactivation of multiple components with orthogonal PI3P/Rab5b marker readouts, epistasis established by double inactivation system; builds on and replicates prior VPS45 findings\",\n      \"pmids\": [\"38820535\"],\n      \"is_preprint\": false,\n      \"attribution\": [\n        {\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}\n      ]\n    }\n  ],\n  \"current_model\": \"In P. falciparum blood-stage parasites, VPS45 (PF3D7_0216400) is an essential endosomal trafficking factor that acts together with Rabenosyn-5-like protein (PfRbsn5L) and PfRab5b — downstream of the PfKelch13 compartment at the parasite plasma membrane — to transport host cell cytosol-filled, PI3P-positive endosomal vesicles to the digestive (food) vacuole for hemoglobin degradation, and is additionally implicated in inner membrane complex biogenesis in coordination with SNARE proteins Stx16 and Stx6.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"VPS45 (PF3D7_0216400) is an essential endosomal trafficking factor in P. falciparum blood-stage parasites that mediates the delivery of host cell cytosol to the digestive (food) vacuole for hemoglobin degradation [#0]. Conditional inactivation of VPS45 blocks hemoglobin delivery and causes accumulation of host cell cytosol-filled vesicles, a proportion of which are decorated with phosphatidylinositol 3-phosphate (PI3P), marking them as endosomal intermediates, with a consequent arrest of parasite growth [#0]. VPS45 acts within a defined endosomal route together with a parasite Rabenosyn-5-like protein (PfRbsn5L) and PfRab5b — but not PfRab5a — and epistasis analysis places this Rbsn5L/VPS45/Rab5b-dependent step downstream of the PfKelch13 compartment [#2]. Beyond this host cell cytosol uptake pathway, VPS45 is additionally implicated in biogenesis of the inner membrane complex in coordination with the SNARE proteins Stx16 and Stx6 [#1]. No structural or biochemical characterization of the VPS45 protein itself, or of its direct molecular interactions, has been established in the available corpus.\",\n  \"teleology\": [\n    {\n      \"year\": 2018,\n      \"claim\": \"Establishing whether VPS45 has a required role in blood-stage parasite biology, this work showed it is essential for delivering host cell cytosol to the digestive vacuole for hemoglobin degradation.\",\n      \"evidence\": \"DiCre-based conditional inactivation in P. falciparum with fluorescence microscopy, vesicle accumulation phenotyping, and PI3P marker co-localization\",\n      \"pmids\": [\"30581113\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Direct molecular partners of VPS45 mediating vesicle transport not identified\",\n        \"Biochemical/structural basis of VPS45 function not resolved\",\n        \"Whether VPS45 acts in vesicle formation, budding, or fusion not distinguished\"\n      ],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Extending VPS45 function beyond endocytic trafficking, this work implicated it in inner membrane complex (alveoli) biogenesis in coordination with SNARE proteins Stx16 and Stx6.\",\n      \"evidence\": \"Functional genetic analysis of SEC1/Munc18 and SNARE proteins in T. gondii and P. falciparum with vesicular trafficking assays\",\n      \"pmids\": [\"33082261\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"IMC biogenesis role inferred from SNARE partner perturbation rather than direct VPS45 loss-of-function in this context\",\n        \"Direct interaction of VPS45 with Stx16/Stx6 not biochemically demonstrated\",\n        \"Mechanism linking VPS45 to alveolar membrane formation unresolved\"\n      ],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Defining the pathway context of VPS45, this work placed it in a discrete endosomal route with PfRbsn5L and PfRab5b acting downstream of the PfKelch13 compartment.\",\n      \"evidence\": \"Single and conditional double protein inactivation in P. falciparum with PI3P/Rab5b co-localization and epistasis analysis\",\n      \"pmids\": [\"38820535\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Direct physical interaction among VPS45, PfRbsn5L, and PfRab5b not shown biochemically\",\n        \"Specificity determinants selecting Rab5b over Rab5a unknown\",\n        \"Molecular link between the PfKelch13 compartment and the VPS45 step not defined\"\n      ],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The biochemical activity of VPS45, its direct binding partners, and its structural basis for coordinating endosomal transport remain undefined.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"No direct protein-protein interaction data for VPS45 in the corpus\",\n        \"No structural model of VPS45 established\",\n        \"Whether the endosomal and IMC roles are mechanistically related is unknown\"\n      ],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [],\n    \"localization\": [],\n    \"pathway\": [\n      {\"term_id\": \"endosomal transport\", \"supporting_discovery_ids\": [0, 2]},\n      {\"term_id\": \"host cell cytosol uptake / hemoglobin delivery to digestive vacuole\", \"supporting_discovery_ids\": [0, 2]},\n      {\"term_id\": \"inner membrane complex biogenesis\", \"supporting_discovery_ids\": [1]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"PfRbsn5L (Rabenosyn-5-like protein)\",\n      \"PfRab5b\",\n      \"Stx16\",\n      \"Stx6\"\n    ],\n    \"other_free_text\": [\n      \"Essential for P. falciparum blood-stage growth; conditional inactivation causes accumulation of PI3P-positive host cell cytosol-filled vesicles and blocks hemoglobin delivery to the food vacuole [#0]\",\n      \"Acts downstream of the PfKelch13 compartment in the Rbsn5L/VPS45/Rab5b endosomal route [#2]\"\n    ]\n  }\n}","audit_flag":null,"strains":[{"strain":"Pf3D7","gene_id":"PF3D7_0216400","name":null,"product":"vacuolar protein sorting-associated protein 45","uniprot_acc":null,"chromosome":null,"start_pos":null},{"strain":"PbANKA","gene_id":"PBANKA_0313100","name":null,"product":"vacuolar protein sorting-associated protein 45, putative","uniprot_acc":null,"chromosome":null,"start_pos":null},{"strain":"PkH","gene_id":"PKNH_0404500","name":null,"product":"vacuolar protein sorting-associated protein 45, putative","uniprot_acc":null,"chromosome":null,"start_pos":null}],"gene_symbol":"VPS45","evaluation":null}