{"id":"4bb97b57-a237-557c-bb81-540c937f1626","stable_key":"4fef8d72-f107-5eb5-b2fb-483ca85465e0:k2-ubiad1-synthesis","predicate":"supports","statement":"Human UBIAD1 expression supported conversion of labeled vitamin K precursors to MK-4, identified by deuterium NMR.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"context_dependent","is_public":true,"mechanism_event_id":"d6773e9c-2986-5c69-bd81-7feca37e091a","mechanism_event_label":"Cells have an enzyme that can make MK-4 from vitamin K precursors.","subject":{"id":"190c8a9f-60f4-5341-898e-187a0c697624","slug":"ubiad1","display_name":"Human UBIAD1 prenyltransferase","entity_type_key":"protein"},"object":{"id":"c06c54bb-69ce-58a3-a904-0647dbaf3577","slug":"mk4-biosynthesis","display_name":"Menaquinone-4 biosynthesis","entity_type_key":"cellular_process"},"evidence_count":1,"mechanism_event":{"id":"d6773e9c-2986-5c69-bd81-7feca37e091a","stable_key":"4fef8d72-f107-5eb5-b2fb-483ca85465e0:k2-ubiad1-synthesis-event","event_type":"biochemical_relationship","label":"Cells have an enzyme that can make MK-4 from vitamin K precursors.","description":"Human UBIAD1 expression supported conversion of labeled vitamin K precursors to MK-4, identified by deuterium NMR.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"5155b9d1-e835-54b4-9f61-4cf35b3e5227","slug":"menaquinone-4","display_name":"Menaquinone-4 / MK-4 / menatetrenone","entity_type_key":"small_molecule"},"role":"product","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"b5cf80a2-c423-5ff5-806e-fa37ddaf7303","slug":"k2","display_name":"Vitamin K2 / menaquinone family","entity_type_key":"chemical_species"},"role":"product_family","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":"c06c54bb-69ce-58a3-a904-0647dbaf3577","slug":"mk4-biosynthesis","display_name":"Menaquinone-4 biosynthesis","entity_type_key":"cellular_process"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":3,"notes":""}]},"contexts":[{"dimension":"evidence_span","value_text":"{\"source_cache\": \"artifacts/k2-research/20953171.abstract.txt\", \"locator\": \"Exact primary indexed abstract; zero-based, end-exclusive Unicode character offsets\", \"file_sha256\": \"b8786e664d3b32db7b0cca72c710e24f1546e14f0a69c031908400731174cea3\", \"start_char\": 0, \"end_char\": 2006, \"text_sha256\": \"b8786e664d3b32db7b0cca72c710e24f1546e14f0a69c031908400731174cea3\"}","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Gene knockdown, heterologous expression, isotope conversion and NMR","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"exposure","value_text":"Labeled vitamin K precursors, UBIAD1 knockdown and expression","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Identifies a biosynthetic enzyme, not a clinical requirement to supplement MK-4. K1-derived MK-4 synthesis does not make humans independent of external vitamin K precursors.","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":"Human UBIAD1 in human and insect-cell systems; mouse localization","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"Cells have an enzyme that can make MK-4 from vitamin K precursors.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[k2-p20953171] Identification of UBIAD1 as a novel human menaquinone-4 biosynthetic enzyme. (2010). https://pubmed.ncbi.nlm.nih.gov/20953171/ DOI: 10.1038/nature09464","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"MK-4 synthesis","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"324f8b08-ff81-5c86-9a2b-1b808c877487","evidence_kind":"source_excerpt","locator":"Lines 136-147","start_line":136,"end_line":147,"excerpt":"### k2-ubiad1-synthesis\nHuman UBIAD1 expression supported conversion of labeled vitamin K precursors to MK-4, identified by deuterium NMR.\nCondition category: normal\nnutrient_topic: Vitamin K2 research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: Cells have an enzyme that can make MK-4 from vitamin K precursors.\norganism: Human UBIAD1 in human and insect-cell systems; mouse localization\ntissue_or_cell_type: MK-4 synthesis\nexperimental_model: Gene knockdown, heterologous expression, isotope conversion and NMR\nlimitations: Identifies a biosynthetic enzyme, not a clinical requirement to supplement MK-4. K1-derived MK-4 synthesis does not make humans independent of external vitamin K precursors.\nexposure: Labeled vitamin K precursors, UBIAD1 knockdown and expression\nevidence_span: {\"source_cache\": \"artifacts/k2-research/20953171.abstract.txt\", \"locator\": \"Exact primary indexed abstract; zero-based, end-exclusive Unicode character offsets\", \"file_sha256\": \"b8786e664d3b32db7b0cca72c710e24f1546e14f0a69c031908400731174cea3\", \"start_char\": 0, \"end_char\": 2006, \"text_sha256\": \"b8786e664d3b32db7b0cca72c710e24f1546e14f0a69c031908400731174cea3\"}\n[k2-p20953171] Identification of UBIAD1 as a novel human menaquinone-4 biosynthetic enzyme. (2010). https://pubmed.ncbi.nlm.nih.gov/20953171/ DOI: 10.1038/nature09464","model_system":"Gene knockdown, heterologous expression, isotope conversion and NMR","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [k2-p20953171] Identification of UBIAD1 as a novel human menaquinone-4 biosynthetic enzyme. (2010). https://pubmed.ncbi.nlm.nih.gov/20953171/ DOI: 10.1038/nature09464","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"dfeae572-af3d-5042-a10e-e67596f9ab28","stable_key":"import-4fef8d72-f107-5eb5-b2fb-483ca85465e0","title":"Vitamin K2: menaquinone forms, carboxylation, recycling and nutrient interactions (2026-09-17)","document_type":"imported_text","citation_label":"AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text.","file_path":"","sha256":"dc31aff21110d09b025c177e03b4c5ca8349d52bf5f962285fdbfcf660c0e4f6","revision_id":"850887db-34f6-55aa-9d3e-b8fd3a4a5de3","review_status":"unverified_draft","notes":""}}],"relations":[],"conflicts":[],"corrections":[],"research":null}