{"id":"86538d4c-ee94-5b34-aab4-4a6b83b9066f","stable_key":"4fef8d72-f107-5eb5-b2fb-483ca85465e0:k2-reduced-precursor","predicate":"uses_reduced_precursor","statement":"Product analysis identified reduced menadione, rather than its quinone form, as an intermediate in UBIAD1-mediated MK-4 formation.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"context_dependent","is_public":true,"mechanism_event_id":"e4a847b0-edc7-57b6-bf6d-7c83adfbdbf7","mechanism_event_label":"The precursor must also be in the right redox state.","subject":{"id":"190c8a9f-60f4-5341-898e-187a0c697624","slug":"ubiad1","display_name":"Human UBIAD1 prenyltransferase","entity_type_key":"protein"},"object":{"id":"40f3d3fe-817b-5d09-ad98-4ac06d340405","slug":"menadiol","display_name":"Menadiol / reduced menadione","entity_type_key":"small_molecule"},"evidence_count":1,"mechanism_event":{"id":"e4a847b0-edc7-57b6-bf6d-7c83adfbdbf7","stable_key":"4fef8d72-f107-5eb5-b2fb-483ca85465e0:k2-reduced-precursor-event","event_type":"biochemical_relationship","label":"The precursor must also be in the right redox state.","description":"Product analysis identified reduced menadione, rather than its quinone form, as an intermediate in UBIAD1-mediated MK-4 formation.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"5fbc279d-45c2-5300-a1ee-b600581bf440","slug":"menadione","display_name":"Menadione / vitamin K3","entity_type_key":"small_molecule"},"role":"oxidized_precursor","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"5155b9d1-e835-54b4-9f61-4cf35b3e5227","slug":"menaquinone-4","display_name":"Menaquinone-4 / MK-4 / menatetrenone","entity_type_key":"small_molecule"},"role":"biosynthetic_product","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"190c8a9f-60f4-5341-898e-187a0c697624","slug":"ubiad1","display_name":"Human UBIAD1 prenyltransferase","entity_type_key":"protein"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""},{"entity":{"id":"40f3d3fe-817b-5d09-ad98-4ac06d340405","slug":"menadiol","display_name":"Menadiol / reduced menadione","entity_type_key":"small_molecule"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":3,"notes":""}]},"contexts":[{"dimension":"evidence_span","value_text":"{\"source_cache\": \"artifacts/k2-research/24085302.abstract.txt\", \"locator\": \"Exact primary indexed abstract; zero-based, end-exclusive Unicode character offsets\", \"file_sha256\": \"a0197882d517aa2bd4d9b2919e72c588383ad183064f1a2bf8f64f5152d28386\", \"start_char\": 0, \"end_char\": 1653, \"text_sha256\": \"a0197882d517aa2bd4d9b2919e72c588383ad183064f1a2bf8f64f5152d28386\"}","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Stable-isotope cannulation and recombinant-enzyme product analysis","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"exposure","value_text":"Oral labeled phylloquinone; MS and NMR analysis","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Rat tracing defines a precursor route; no exact human conversion fraction or advice to ingest menadione is inferred.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Vitamin K2 research collection; topical membership is not evidence of a direct dietary effect.","comparator":null,"unit":null,"notes":"","entity":{"slug":"k2","display_name":"Vitamin K2 / menaquinone family","entity_type_key":"chemical_species"}},{"dimension":"organism","value_text":"Rats and recombinant UBIAD1","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"The precursor must also be in the right redox state.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[k2-p24085302] Menadione (vitamin K3) is a catabolic product of oral phylloquinone (vitamin K1) in the intestine and a circulating precursor of tissue menaquinone-4 (vitamin K2) in rats. 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(2013). https://pubmed.ncbi.nlm.nih.gov/24085302/ DOI: 10.1074/jbc.m113.477356","model_system":"Stable-isotope cannulation and recombinant-enzyme product analysis","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [k2-p24085302] Menadione (vitamin K3) is a catabolic product of oral phylloquinone (vitamin K1) in the intestine and a circulating precursor of tissue menaquinone-4 (vitamin K2) in rats. 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