{"id":"988bd0ca-ad25-5a18-9ae5-a1cdb13ecaf1","stable_key":"434e1e27-eb90-583a-956b-62472726ffba:cyp24a1-calcitriol-c24-hydroxylation","predicate":"produces","statement":"Human CYP24A1 hydroxylates calcitriol to 1-alpha,24,25-trihydroxyvitamin D3 in the first C24-oxidation step.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"context_dependent","is_public":true,"mechanism_event_id":"8a2da43a-3ada-586f-aeeb-7b0c271c9586","mechanism_event_label":"CYP24A1 begins a defined calcitriol breakdown route.","subject":{"id":"c0a944e7-deb8-5f9e-8428-91496098e38f","slug":"cyp24a1","display_name":"Vitamin D 24-hydroxylase / CYP24A1","entity_type_key":"protein"},"object":{"id":"a12541e6-4fb6-50d1-98b7-d114c993c8fb","slug":"1-24-25-trihydroxyvitamin-d3","display_name":"1-alpha,24,25-Trihydroxyvitamin D3","entity_type_key":"small_molecule"},"evidence_count":1,"mechanism_event":{"id":"8a2da43a-3ada-586f-aeeb-7b0c271c9586","stable_key":"434e1e27-eb90-583a-956b-62472726ffba:cyp24a1-calcitriol-c24-hydroxylation-event","event_type":"biochemical_reaction","label":"CYP24A1 begins a defined calcitriol breakdown route.","description":"Human CYP24A1 hydroxylates calcitriol to 1-alpha,24,25-trihydroxyvitamin D3 in the first C24-oxidation step.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"c0a944e7-deb8-5f9e-8428-91496098e38f","slug":"cyp24a1","display_name":"Vitamin D 24-hydroxylase / CYP24A1","entity_type_key":"protein"},"role":"enzyme","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"f5156c24-108f-5746-b114-ed764e79a3f4","slug":"calcitriol","display_name":"Calcitriol","entity_type_key":"small_molecule"},"role":"substrate","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"a12541e6-4fb6-50d1-98b7-d114c993c8fb","slug":"1-24-25-trihydroxyvitamin-d3","display_name":"1-alpha,24,25-Trihydroxyvitamin D3","entity_type_key":"small_molecule"},"role":"product","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""}]},"contexts":[{"dimension":"experimental_model","value_text":"Human CYP24A1 expressed in E. coli, partially purified and reconstituted in phospholipid vesicles","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"This is a C24-pathway intermediate, not a final inactive product. Further oxidation and the distinct C23 route are not represented by this single edge.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Calcium research collection; topical membership is not evidence of a direct dietary effect.","comparator":null,"unit":null,"notes":"","entity":{"slug":"calcium","display_name":"Calcium","entity_type_key":"nutrient_element"}},{"dimension":"organism","value_text":"Homo sapiens enzyme","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"CYP24A1 begins a defined calcitriol breakdown route.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[tieu2014] Kinetic analysis of human CYP24A1 metabolism of vitamin D via the C24-oxidation pathway (2014). https://pubmed.ncbi.nlm.nih.gov/24893882/ DOI: 10.1111/febs.12862","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"research_relationship_category","value_text":"biochemical_reaction","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Reconstituted enzyme/membrane system","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"transport_or_reaction_direction","value_text":"forward","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"340a3a8b-86bb-542d-82d4-5fb6290dee03","evidence_kind":"source_excerpt","locator":"Lines 362-373","start_line":362,"end_line":373,"excerpt":"### cyp24a1-calcitriol-c24-hydroxylation\nHuman CYP24A1 hydroxylates calcitriol to 1-alpha,24,25-trihydroxyvitamin D3 in the first C24-oxidation step.\nCondition category: normal\nnutrient_topic: Calcium research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: CYP24A1 begins a defined calcitriol breakdown route.\norganism: Homo sapiens enzyme\ntissue_or_cell_type: Reconstituted enzyme/membrane system\nexperimental_model: Human CYP24A1 expressed in E. coli, partially purified and reconstituted in phospholipid vesicles\nlimitations: This is a C24-pathway intermediate, not a final inactive product. Further oxidation and the distinct C23 route are not represented by this single edge.\nresearch_relationship_category: biochemical_reaction\ntransport_or_reaction_direction: forward\n[tieu2014] Kinetic analysis of human CYP24A1 metabolism of vitamin D via the C24-oxidation pathway (2014). https://pubmed.ncbi.nlm.nih.gov/24893882/ DOI: 10.1111/febs.12862","model_system":"Human CYP24A1 expressed in E. coli, partially purified and reconstituted in phospholipid vesicles","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [tieu2014] Kinetic analysis of human CYP24A1 metabolism of vitamin D via the C24-oxidation pathway (2014). https://pubmed.ncbi.nlm.nih.gov/24893882/ DOI: 10.1111/febs.12862","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"3c083fa0-59c6-50e9-af42-678d0e3c1006","stable_key":"import-434e1e27-eb90-583a-956b-62472726ffba","title":"Calcium: mechanism-first literature curation (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":"965c934d6b147f2b62f8d45ce6d7a87681a600bfe5c46a585b4704889afd3fc1","revision_id":"543ec48b-4f70-5197-9d76-f5a3c443664c","review_status":"unverified_draft","notes":""}}],"relations":[],"conflicts":[],"corrections":[],"research":null}