{"id":"035dd14d-4f8a-5e25-8833-fb41057a9ca5","stable_key":"7fc92b9e-9cbf-556e-8719-6b5244625250:mmaa-exposes-mmut-cobalamin-domain","predicate":"stabilizes","statement":"The human MMUT-MMAA structure showed MMAA stabilizing a roughly 180-degree rotation that exposed the MMUT B12-binding domain.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"positive","is_public":true,"mechanism_event_id":"e19cf703-b942-596b-aeca-298a1a82cac6","mechanism_event_label":"The human-protein structure showed how MMAA opens access to MMUT-bound B12.","subject":{"id":"39366dce-a30d-5e74-8c86-2bd8ca0bad96","slug":"mmaa","display_name":"Human MMAA GTPase","entity_type_key":"protein"},"object":{"id":"268626c1-6a05-5a8e-a886-c9cd205ad73d","slug":"mmut-cofactor-site-exposure","display_name":"Exposure of the human MMUT cobalamin-binding domain","entity_type_key":"cellular_process"},"evidence_count":1,"mechanism_event":{"id":"e19cf703-b942-596b-aeca-298a1a82cac6","stable_key":"7fc92b9e-9cbf-556e-8719-6b5244625250:mmaa-exposes-mmut-cobalamin-domain-event","event_type":"biochemical_relationship","label":"The human-protein structure showed how MMAA opens access to MMUT-bound B12.","description":"The human MMUT-MMAA structure showed MMAA stabilizing a roughly 180-degree rotation that exposed the MMUT B12-binding domain.","status":"provisional","compartment":{"slug":"mitochondrial-matrix","display_name":"Mitochondrial matrix"},"participants":[{"entity":{"id":"8f690797-c976-5a5e-886e-dc49d1b17f5a","slug":"mmut","display_name":"Human methylmalonyl-CoA mutase / MMUT","entity_type_key":"protein"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"bff427ab-35f9-59c2-bb24-fd5953bbaec2","slug":"magnesium-ion","display_name":"Mg2+","entity_type_key":"ion"},"role":"nucleotide-site-ion","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"9624279a-7bf6-5f6e-bf30-bb5f6a09fcfe","slug":"human-mmaa-mmut-complex","display_name":"Human MMAA-MMUT complex","entity_type_key":"protein_complex"},"role":"complex","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""},{"entity":{"id":"39366dce-a30d-5e74-8c86-2bd8ca0bad96","slug":"mmaa","display_name":"Human MMAA GTPase","entity_type_key":"protein"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":3,"notes":""},{"entity":{"id":"268626c1-6a05-5a8e-a886-c9cd205ad73d","slug":"mmut-cofactor-site-exposure","display_name":"Exposure of the human MMUT cobalamin-binding domain","entity_type_key":"cellular_process"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":4,"notes":""}]},"contexts":[{"dimension":"cross_nutrient","value_text":"false","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"evidence_location","value_text":"Full text Results; Figures 2-4; cofactor off-loading and MMUT activity Methods","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Purified human proteins","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"exposure","value_text":"Crystallized complex with CoA, GDP and Mg2+","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Static structure; does not directly measure the complete loading trajectory.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Vitamin B12 research collection; topical membership is not evidence of a direct dietary effect.","comparator":null,"unit":null,"notes":"","entity":{"slug":"vitamin-b12","display_name":"Vitamin B12 (cobalamins)","entity_type_key":"chemical_species"}},{"dimension":"organism","value_text":"Homo sapiens","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"The human-protein structure showed how MMAA opens access to MMUT-bound B12.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[mascarenhas-2023-nanoassembly] Architecture of the human G-protein-methylmalonyl-CoA mutase nanoassembly for B12 delivery and repair. (2023). https://pubmed.ncbi.nlm.nih.gov/37468522/ DOI: 10.1038/s41467-023-40077-4","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Purified protein assay","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"955bb34d-83b9-5a76-9136-53741035a29f","evidence_kind":"source_excerpt","locator":"Lines 1117-1129","start_line":1117,"end_line":1129,"excerpt":"### mmaa-exposes-mmut-cobalamin-domain\nThe human MMUT-MMAA structure showed MMAA stabilizing a roughly 180-degree rotation that exposed the MMUT B12-binding domain.\nCondition category: normal\nnutrient_topic: Vitamin B12 research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: The human-protein structure showed how MMAA opens access to MMUT-bound B12.\norganism: Homo sapiens\ntissue_or_cell_type: Purified protein assay\nexperimental_model: Purified human proteins\nlimitations: Static structure; does not directly measure the complete loading trajectory.\nexposure: Crystallized complex with CoA, GDP and Mg2+\ncross_nutrient: false\nevidence_location: Full text Results; Figures 2-4; cofactor off-loading and MMUT activity Methods\n[mascarenhas-2023-nanoassembly] Architecture of the human G-protein-methylmalonyl-CoA mutase nanoassembly for B12 delivery and repair. 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