{"gene":"PF3D7_1232300","run_date":"2026-09-08T14:19:06","timeline":{"discoveries":[{"year":2010,"finding":"The product of PF3D7_1232300 (PFL1555w), a putative cytochrome b5, localizes to the food vacuole (FV) membrane of P. falciparum trophozoites, co-localizing with a putative cytochrome b5 reductase (PF13_0353); together they may contribute to NO generation via denitrification chemistry from nitrate/nitrite derived from erythrocyte cytosol.","method":"Subcellular localization by direct imaging/fractionation of food vacuoles; resonance Raman spectroscopy of intact FVs","journal":"Experimental parasitology","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, single localization experiment with no functional mutagenesis or reconstitution; denitrification role is proposed but not experimentally confirmed for this specific protein","pmids":["20493843"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]}],"current_model":"PF3D7_1232300 (putative cytochrome b5) localizes to the food vacuole membrane of P. falciparum trophozoites alongside a putative cytochrome b5 reductase, suggesting a possible role in NO generation by denitrification within the food vacuole, but no direct enzymatic activity or mechanistic pathway has been experimentally confirmed for this protein."},"narrative":{"mechanistic_narrative":"PF3D7_1232300 is a putative cytochrome b5 of Plasmodium falciparum whose product localizes to the food vacuole membrane of trophozoites, where it co-localizes with a putative cytochrome b5 reductase (PF13_0353) [PMID:20493843]. This co-localization has led to the proposal that the two proteins together contribute to nitric oxide generation via denitrification chemistry acting on nitrate/nitrite derived from erythrocyte cytosol [PMID:20493843]. Beyond this single localization observation, no direct enzymatic activity, substrate, or mechanistic pathway has been experimentally confirmed for PF3D7_1232300 in the available corpus.","teleology":[{"year":2010,"claim":"Whether a Plasmodium cytochrome b5 has a defined subcellular home was unknown; imaging placed the PF3D7_1232300 product at the food vacuole membrane alongside a putative cytochrome b5 reductase, establishing a candidate redox module at this organelle.","evidence":"Subcellular localization by direct imaging/fractionation of food vacuoles and resonance Raman spectroscopy of intact food vacuoles in P. falciparum trophozoites","pmids":["20493843"],"confidence":"Low","gaps":["Single-lab localization experiment with no functional mutagenesis, knockout, or reconstitution to test the proposed denitrification role","No direct measurement of enzymatic activity or electron-transfer function for PF3D7_1232300 itself","Co-localization with PF13_0353 does not establish a physical complex or functional coupling"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":null,"claim":"It remains unknown whether PF3D7_1232300 possesses any cytochrome b5 redox activity and whether it functionally participates in food-vacuole nitric oxide generation.","evidence":"","pmids":[],"confidence":"Low","gaps":["No biochemical reconstitution of PF3D7_1232300 with its putative reductase partner","No genetic evidence linking PF3D7_1232300 to NO/denitrification chemistry","No structural or heme-binding characterization of the protein"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]}],"mechanism_profile":{"molecular_activity":[],"localization":[],"pathway":[],"complexes":[],"partners":["PF13_0353 (PUTATIVE CYTOCHROME B5 REDUCTASE, CO-LOCALIZES AT FOOD VACUOLE MEMBRANE) [#0]"],"other_free_text":["Putative cytochrome b5 localizing to the food vacuole membrane of P. falciparum trophozoites [#0].","Proposed but experimentally unconfirmed contribution to nitric oxide generation via denitrification of erythrocyte-derived nitrate/nitrite [#0]."]}},"prefetch_data":{},"corpus_meta":[{"pmid":"20493843","id":"PMC_20493843","title":"Plasmodium falciparum: nitric oxide modulates heme speciation in isolated food vacuoles.","date":"2010","source":"Experimental parasitology","url":"https://pubmed.ncbi.nlm.nih.gov/20493843","citation_count":13,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["PFL1555w"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":3274,"output_tokens":411,"usd":0.007994,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":4891,"output_tokens":1146,"usd":0.026552,"stage2_stop_reason":"end_turn"},"total_usd":0.034546,"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\": 2010,\n      \"finding\": \"The product of PF3D7_1232300 (PFL1555w), a putative cytochrome b5, localizes to the food vacuole (FV) membrane of P. falciparum trophozoites, co-localizing with a putative cytochrome b5 reductase (PF13_0353); together they may contribute to NO generation via denitrification chemistry from nitrate/nitrite derived from erythrocyte cytosol.\",\n      \"method\": \"Subcellular localization by direct imaging/fractionation of food vacuoles; resonance Raman spectroscopy of intact FVs\",\n      \"journal\": \"Experimental parasitology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, single localization experiment with no functional mutagenesis or reconstitution; denitrification role is proposed but not experimentally confirmed for this specific protein\",\n      \"pmids\": [\"20493843\"],\n      \"is_preprint\": false,\n      \"attribution\": [\n        {\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}\n      ]\n    }\n  ],\n  \"current_model\": \"PF3D7_1232300 (putative cytochrome b5) localizes to the food vacuole membrane of P. falciparum trophozoites alongside a putative cytochrome b5 reductase, suggesting a possible role in NO generation by denitrification within the food vacuole, but no direct enzymatic activity or mechanistic pathway has been experimentally confirmed for this protein.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"PF3D7_1232300 is a putative cytochrome b5 of Plasmodium falciparum whose product localizes to the food vacuole membrane of trophozoites, where it co-localizes with a putative cytochrome b5 reductase (PF13_0353) [#0]. This co-localization has led to the proposal that the two proteins together contribute to nitric oxide generation via denitrification chemistry acting on nitrate/nitrite derived from erythrocyte cytosol [#0]. Beyond this single localization observation, no direct enzymatic activity, substrate, or mechanistic pathway has been experimentally confirmed for PF3D7_1232300 in the available corpus.\",\n  \"teleology\": [\n    {\n      \"year\": 2010,\n      \"claim\": \"Whether a Plasmodium cytochrome b5 has a defined subcellular home was unknown; imaging placed the PF3D7_1232300 product at the food vacuole membrane alongside a putative cytochrome b5 reductase, establishing a candidate redox module at this organelle.\",\n      \"evidence\": \"Subcellular localization by direct imaging/fractionation of food vacuoles and resonance Raman spectroscopy of intact food vacuoles in P. falciparum trophozoites\",\n      \"pmids\": [\"20493843\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"Single-lab localization experiment with no functional mutagenesis, knockout, or reconstitution to test the proposed denitrification role\",\n        \"No direct measurement of enzymatic activity or electron-transfer function for PF3D7_1232300 itself\",\n        \"Co-localization with PF13_0353 does not establish a physical complex or functional coupling\"\n      ],\n      \"attribution\": [\n        {\n          \"species\": \"Plasmodium falciparum\",\n          \"strain\": \"\"\n        }\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"It remains unknown whether PF3D7_1232300 possesses any cytochrome b5 redox activity and whether it functionally participates in food-vacuole nitric oxide generation.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"No biochemical reconstitution of PF3D7_1232300 with its putative reductase partner\",\n        \"No genetic evidence linking PF3D7_1232300 to NO/denitrification chemistry\",\n        \"No structural or heme-binding characterization of the protein\"\n      ],\n      \"attribution\": [\n        {\n          \"species\": \"Plasmodium falciparum\",\n          \"strain\": \"\"\n        }\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [],\n    \"localization\": [\n      {\"term_id\": \"GO:0034426\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"pathway\": [],\n    \"complexes\": [],\n    \"partners\": [\"PF13_0353 (putative cytochrome b5 reductase, co-localizes at food vacuole membrane) [#0]\"],\n    \"other_free_text\": [\n      \"Putative cytochrome b5 localizing to the food vacuole membrane of P. falciparum trophozoites [#0].\",\n      \"Proposed but experimentally unconfirmed contribution to nitric oxide generation via denitrification of erythrocyte-derived nitrate/nitrite [#0].\"\n    ]\n  }\n}","audit_flag":null,"strains":[{"strain":"Pf3D7","gene_id":"PF3D7_1232300","name":null,"product":"cytochrome b5, putative","uniprot_acc":null,"chromosome":null,"start_pos":null},{"strain":"PbANKA","gene_id":"PBANKA_1447000","name":null,"product":"cytochrome b5, putative","uniprot_acc":null,"chromosome":null,"start_pos":null},{"strain":"PkH","gene_id":"PKNH_1451800","name":null,"product":"cytochrome b5, putative","uniprot_acc":null,"chromosome":null,"start_pos":null}],"gene_symbol":"","evaluation":null}