{"id":"7bc5fcaa-b311-54cc-a6d1-6d8fa5360d6d","stable_key":"dc8975b1-95ff-5d9b-be17-a1c04610cca7:mo-cyb5b-heme","predicate":"is_required_for_electron_transfer_by","statement":"Heme-free apo-CYB5 failed to support N-reduction in the reconstituted system.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"context_dependent","is_public":true,"mechanism_event_id":"8ba96a73-1572-59ba-a1d3-2ba479b87c02","mechanism_event_label":"Removing the iron-containing heme breaks this electron-transfer step.","subject":{"id":"2e1f7e0a-8b54-5ea3-9d34-01e7167f9097","slug":"heme","display_name":"Heme","entity_type_key":"small_molecule"},"object":{"id":"2cf304f6-f587-510a-9976-765f8d9ee83a","slug":"cyb5b","display_name":"Human mitochondrial cytochrome b5 / CYB5B","entity_type_key":"protein"},"evidence_count":1,"mechanism_event":{"id":"8ba96a73-1572-59ba-a1d3-2ba479b87c02","stable_key":"dc8975b1-95ff-5d9b-be17-a1c04610cca7:mo-cyb5b-heme-event","event_type":"biochemical_relationship","label":"Removing the iron-containing heme breaks this electron-transfer step.","description":"Heme-free apo-CYB5 failed to support N-reduction in the reconstituted system.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"cd629c45-47a6-555e-9ad9-9abb93a04e7f","slug":"mtarc1","display_name":"Human mitochondrial amidoxime-reducing component 1 / MTARC1","entity_type_key":"protein"},"role":"terminal enzyme","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"89bcaf42-b4ab-5760-8c2e-44eace10cee0","slug":"iron","display_name":"Iron","entity_type_key":"nutrient_element"},"role":"heme constituent","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"2e1f7e0a-8b54-5ea3-9d34-01e7167f9097","slug":"heme","display_name":"Heme","entity_type_key":"small_molecule"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""},{"entity":{"id":"2cf304f6-f587-510a-9976-765f8d9ee83a","slug":"cyb5b","display_name":"Human mitochondrial cytochrome b5 / CYB5B","entity_type_key":"protein"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":3,"notes":""}]},"contexts":[{"dimension":"evidence_span","value_text":"{\"source_cache\": \"artifacts/molybdenum-research/23703616.abstract.txt\", \"locator\": \"Exact primary indexed abstract; zero-based, end-exclusive Unicode character offsets\", \"file_sha256\": \"9034da6c790ca6e0c60dd765eec631ea2875c6caf65f6d15d59733bc5e0ee0ec\", \"start_char\": 0, \"end_char\": 1596, \"text_sha256\": \"9034da6c790ca6e0c60dd765eec631ea2875c6caf65f6d15d59733bc5e0ee0ec\"}","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Human-cell siRNA plus recombinant cytochrome-b5/cofactor reconstitution","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"exposure","value_text":"mARC, CYB5B and CYB5A depletion; apo-CYB5","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Expression-dependent cellular contributions; no clinical iron or B2 supplementation test.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Molybdenum research collection; topical membership is not evidence of a direct dietary effect.","comparator":null,"unit":null,"notes":"","entity":{"slug":"molybdenum","display_name":"Molybdenum","entity_type_key":"nutrient_element"}},{"dimension":"organism","value_text":"Homo sapiens; separate mouse Cyb5a knockout","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"Removing the iron-containing heme breaks this electron-transfer step.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[mo-p23703616] The involvement of mitochondrial amidoxime reducing components 1 and 2 and mitochondrial cytochrome b5 in N-reductive metabolism in human cells. (2013). https://pubmed.ncbi.nlm.nih.gov/23703616/ DOI: 10.1074/jbc.m113.474916","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"HEK293 and second human cell line; purified proteins","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"2a4604e7-c847-56fa-8a22-5caad5bd7337","evidence_kind":"source_excerpt","locator":"Lines 1002-1013","start_line":1002,"end_line":1013,"excerpt":"### mo-cyb5b-heme\nHeme-free apo-CYB5 failed to support N-reduction in the reconstituted system.\nCondition category: normal\nnutrient_topic: Molybdenum research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: Removing the iron-containing heme breaks this electron-transfer step.\norganism: Homo sapiens; separate mouse Cyb5a knockout\ntissue_or_cell_type: HEK293 and second human cell line; purified proteins\nexperimental_model: Human-cell siRNA plus recombinant cytochrome-b5/cofactor reconstitution\nlimitations: Expression-dependent cellular contributions; no clinical iron or B2 supplementation test.\nexposure: mARC, CYB5B and CYB5A depletion; apo-CYB5\nevidence_span: {\"source_cache\": \"artifacts/molybdenum-research/23703616.abstract.txt\", \"locator\": \"Exact primary indexed abstract; zero-based, end-exclusive Unicode character offsets\", \"file_sha256\": \"9034da6c790ca6e0c60dd765eec631ea2875c6caf65f6d15d59733bc5e0ee0ec\", \"start_char\": 0, \"end_char\": 1596, \"text_sha256\": \"9034da6c790ca6e0c60dd765eec631ea2875c6caf65f6d15d59733bc5e0ee0ec\"}\n[mo-p23703616] The involvement of mitochondrial amidoxime reducing components 1 and 2 and mitochondrial cytochrome b5 in N-reductive metabolism in human cells. 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