{"id":"82fe23a9-7a4f-5315-830b-c3c3ce763df5","stable_key":"41a89233-da9a-5b7b-9c18-e19bbadcfe2d:methionine-mat1-isoenzymes","predicate":"forms","statement":"MAT1A supplies subunits of tetrameric MAT I and dimeric MAT III, which convert methionine and ATP to SAM.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"context_dependent","is_public":true,"mechanism_event_id":"3b9287fc-bbe8-51b0-b10b-7d5a6420060a","mechanism_event_label":"The liver has distinct enzyme assemblies for activating methionine.","subject":{"id":"7fdec12b-82f3-5c55-88fb-32428555c7c6","slug":"mat1a","display_name":"Human methionine adenosyltransferase 1A / MAT1A","entity_type_key":"protein"},"object":{"id":"b9574e9a-32df-5d5d-ab33-0ac6a76e28f8","slug":"human-mat-i-iii","display_name":"Human hepatic MAT I / MAT III isoenzymes","entity_type_key":"protein_set"},"evidence_count":1,"mechanism_event":{"id":"3b9287fc-bbe8-51b0-b10b-7d5a6420060a","stable_key":"41a89233-da9a-5b7b-9c18-e19bbadcfe2d:methionine-mat1-isoenzymes-event","event_type":"observed_relationship","label":"The liver has distinct enzyme assemblies for activating methionine.","description":"MAT1A supplies subunits of tetrameric MAT I and dimeric MAT III, which convert methionine and ATP to SAM.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"7fdec12b-82f3-5c55-88fb-32428555c7c6","slug":"mat1a","display_name":"Human methionine adenosyltransferase 1A / MAT1A","entity_type_key":"protein"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"b9574e9a-32df-5d5d-ab33-0ac6a76e28f8","slug":"human-mat-i-iii","display_name":"Human hepatic MAT I / MAT III isoenzymes","entity_type_key":"protein_set"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"9d39f561-740b-5f67-bba7-8a72ef612a99","slug":"methionine","display_name":"L-Methionine","entity_type_key":"small_molecule"},"role":"context_participant","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""},{"entity":{"id":"58b974f1-d389-5bf6-81cd-889c44442c42","slug":"atp","display_name":"ATP","entity_type_key":"small_molecule"},"role":"context_participant","stoichiometry":null,"state_label":"","sequence_order":3,"notes":""},{"entity":{"id":"825f2da2-01bc-5874-a3c6-64f5ac867db5","slug":"s-adenosylmethionine","display_name":"S-Adenosyl-L-methionine","entity_type_key":"small_molecule"},"role":"context_participant","stoichiometry":null,"state_label":"","sequence_order":4,"notes":""}]},"contexts":[{"dimension":"evidence_access","value_text":"Primary abstract","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Human MAT1A disease cohort; established isoenzyme chemistry.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"MAT1A and MAT2A retain separate identities.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"L-Methionine collection; species, compartment, exposure, co-substrates and manipulation remain explicit.","comparator":null,"unit":null,"notes":"","entity":{"slug":"methionine","display_name":"L-Methionine","entity_type_key":"small_molecule"}},{"dimension":"plain_language","value_text":"The liver has distinct enzyme assemblies for activating methionine.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"Mudd's disease (MAT I/III deficiency): a survey of data for MAT1A homozygotes and compound heterozygotes. · 2015 · https://pubmed.ncbi.nlm.nih.gov/26289392/ · DOI 10.1186/s13023-015-0321-y","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"4010de6a-44ad-5f3b-ae4b-0e44178480de","evidence_kind":"source_excerpt","locator":"Lines 148-154","start_line":148,"end_line":154,"excerpt":"## methionine-mat1-isoenzymes\nThe liver has distinct enzyme assemblies for activating methionine.\nMAT1A supplies subunits of tetrameric MAT I and dimeric MAT III, which convert methionine and ATP to SAM.\nModel: Human MAT1A disease cohort; established isoenzyme chemistry.\nLimitations: MAT1A and MAT2A retain separate identities.\nEvidence access: Primary abstract\nMudd's disease (MAT I/III deficiency): a survey of data for MAT1A homozygotes and compound heterozygotes. · 2015 · https://pubmed.ncbi.nlm.nih.gov/26289392/ · DOI 10.1186/s13023-015-0321-y","model_system":"Human MAT1A disease cohort; established isoenzyme chemistry.","directness":"reported_statement","verification_status":"source_derived_draft","notes":"Original curation paraphrase; evidence access and experimental limitations specified.","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"d969b004-ccc2-5bb4-9109-8ac649137ad1","stable_key":"import-41a89233-da9a-5b7b-9c18-e19bbadcfe2d","title":"L-Methionine: transport, methylation, sulfur metabolism and cross-nutrient mechanisms (2026-09-19)","document_type":"imported_text","citation_label":"AI-assisted research curation; primary references, access levels and experimental limitations individually identified. Not publisher full text.","file_path":"","sha256":"f1c706ef72932eed85df234b6c3304158d503d626a63c69b02a453c162700d26","revision_id":"549035e0-3a72-550a-8a55-e8c5baa51b0d","review_status":"unverified_draft","notes":""}}],"relations":[],"conflicts":[],"corrections":[],"research":null}