{"id":"01ce1a37-462c-51e0-963b-4f35e18b56c2","stable_key":"46d15d9e-d3b5-544d-ba01-b785aa3e4f42:b1-bckdh-cofactor-limits-phosphorylation","predicate":"reduces-kinase-phosphorylation-of","statement":"ThDP reduced kinase-mediated phosphorylation of wild-type human E1b; loop-network mutations abolished this protection in the reconstituted assay.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"negative","is_public":true,"mechanism_event_id":"da9837d6-0db1-5c28-8fce-51afc9dbfc61","mechanism_event_label":"Cofactor occupancy also affected access to a regulatory site. The result depends on an intact loop and does not show that every genetic BCKDH defect responds to B1.","subject":{"id":"187db168-8028-5ce6-9f8b-4bc61ebad1a0","slug":"thiamine-diphosphate","display_name":"Thiamine diphosphate","entity_type_key":"small_molecule"},"object":{"id":"82b74ccc-3ee5-5622-a8bd-0691de8cdc54","slug":"bckdh-e1","display_name":"Human branched-chain ketoacid dehydrogenase E1","entity_type_key":"protein_complex"},"evidence_count":1,"mechanism_event":{"id":"da9837d6-0db1-5c28-8fce-51afc9dbfc61","stable_key":"46d15d9e-d3b5-544d-ba01-b785aa3e4f42:b1-bckdh-cofactor-limits-phosphorylation-event","event_type":"biochemical_relationship","label":"Cofactor occupancy also affected access to a regulatory site. The result depends on an intact loop and does not show that every genetic BCKDH defect responds to B1.","description":"ThDP reduced kinase-mediated phosphorylation of wild-type human E1b; loop-network mutations abolished this protection in the reconstituted assay.","status":"provisional","compartment":{"slug":"mitochondrial-matrix","display_name":"Mitochondrial matrix"},"participants":[{"entity":{"id":"58b974f1-d389-5bf6-81cd-889c44442c42","slug":"atp","display_name":"ATP","entity_type_key":"small_molecule"},"role":"phosphate donor","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"99e4447f-bc64-5044-bbc8-cbba58545262","slug":"dbt","display_name":"Dihydrolipoyl branched-chain transacylase / DBT","entity_type_key":"protein"},"role":"E2 scaffold","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"04fe8a1f-172d-5c76-b10a-fb040ec34826","slug":"rat-bckdk","display_name":"Rat branched-chain ketoacid dehydrogenase kinase","entity_type_key":"protein"},"role":"recombinant regulatory kinase","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""},{"entity":{"id":"187db168-8028-5ce6-9f8b-4bc61ebad1a0","slug":"thiamine-diphosphate","display_name":"Thiamine diphosphate","entity_type_key":"small_molecule"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":3,"notes":""},{"entity":{"id":"82b74ccc-3ee5-5622-a8bd-0691de8cdc54","slug":"bckdh-e1","display_name":"Human branched-chain ketoacid dehydrogenase E1","entity_type_key":"protein_complex"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":4,"notes":""}]},"contexts":[{"dimension":"evidence","value_text":"[{\"paper_key\": \"li-2004-bckdh\", \"source_bundle\": \"artifacts/thiamine_metabolism_sources.json\", \"passage_ids\": [\"abstract\"], \"locator\": \"Primary publication abstract\", \"preservation\": \"Exact text retained in the source bundle; full source document retained when openly retrievable.\"}]","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Human E1b/E2b with recombinant rat BCKD kinase.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Mixed-species assay; kinase accessibility, not clinical thiamine responsiveness.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient","value_text":"Thiamine (vitamin B1)","comparator":null,"unit":null,"notes":"","entity":{"slug":"thiamine","display_name":"Thiamine (vitamin B1)","entity_type_key":"small_molecule"}},{"dimension":"nutrient_topic","value_text":"Thiamine research collection; topical membership is not evidence of a direct dietary effect.","comparator":null,"unit":null,"notes":"","entity":{"slug":"thiamine","display_name":"Thiamine (vitamin B1)","entity_type_key":"small_molecule"}},{"dimension":"organism","value_text":"Homo sapiens E1/E2; Rattus norvegicus kinase","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"Cofactor occupancy also affected access to a regulatory site. The result depends on an intact loop and does not show that every genetic BCKDH defect responds to B1.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[li-2004-bckdh] Cross-talk between thiamin diphosphate binding and phosphorylation loop conformation in human branched-chain alpha-keto acid decarboxylase/dehydrogenase (2004). https://pubmed.ncbi.nlm.nih.gov/15166214/ DOI: 10.1074/jbc.m403611200","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Purified mixed-species assay","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"1cdc53bd-ace5-5762-97d7-ab2f5ba4eb3d","evidence_kind":"source_excerpt","locator":"Lines 801-812","start_line":801,"end_line":812,"excerpt":"### b1-bckdh-cofactor-limits-phosphorylation\nThDP reduced kinase-mediated phosphorylation of wild-type human E1b; loop-network mutations abolished this protection in the reconstituted assay.\nCondition category: normal\nnutrient_topic: Thiamine research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: Cofactor occupancy also affected access to a regulatory site. The result depends on an intact loop and does not show that every genetic BCKDH defect responds to B1.\norganism: Homo sapiens E1/E2; Rattus norvegicus kinase\ntissue_or_cell_type: Purified mixed-species assay\nexperimental_model: Human E1b/E2b with recombinant rat BCKD kinase.\nlimitations: Mixed-species assay; kinase accessibility, not clinical thiamine responsiveness.\nevidence: [{\"paper_key\": \"li-2004-bckdh\", \"source_bundle\": \"artifacts/thiamine_metabolism_sources.json\", \"passage_ids\": [\"abstract\"], \"locator\": \"Primary publication abstract\", \"preservation\": \"Exact text retained in the source bundle; full source document retained when openly retrievable.\"}]\nnutrient: Thiamine (vitamin B1)\n[li-2004-bckdh] Cross-talk between thiamin diphosphate binding and phosphorylation loop conformation in human branched-chain alpha-keto acid decarboxylase/dehydrogenase (2004). https://pubmed.ncbi.nlm.nih.gov/15166214/ DOI: 10.1074/jbc.m403611200","model_system":"Human E1b/E2b with recombinant rat BCKD kinase.","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [li-2004-bckdh] Cross-talk between thiamin diphosphate binding and phosphorylation loop conformation in human branched-chain alpha-keto acid decarboxylase/dehydrogenase (2004). https://pubmed.ncbi.nlm.nih.gov/15166214/ DOI: 10.1074/jbc.m403611200","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"158d2c03-ac8c-589f-8270-c468165ae346","stable_key":"import-46d15d9e-d3b5-544d-ba01-b785aa3e4f42","title":"Thiamine: mechanisms, deficiency 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":"f376512fb3310141315548015b387833e3af45146e73fb73cd02cee20e4ddb9c","revision_id":"53bc5eda-dec8-58cc-a56f-a9eb4ab036ef","review_status":"unverified_draft","notes":""}}],"relations":[],"conflicts":[],"corrections":[],"research":null}