{"id":"e209d990-4654-540c-b032-91608dfb4c6e","stable_key":"548ab9d6-3a9b-5bed-879c-17d03813b636:b2-txnrd1-terminal-relay","predicate":"supports-modeled-reduction-of","statement":"A rat TXNRD1 structure and docking model with human thioredoxin support a relay through the opposite subunit and C-terminal tail toward the substrate.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"positive","is_public":true,"mechanism_event_id":"7dee368e-4243-5930-87b9-7381dce18356","mechanism_event_label":"A second redox center carries electrons onward to thioredoxin.","subject":{"id":"44c93642-76cb-5254-9edb-14a3020a5ae6","slug":"rat-txnrd1","display_name":"Rat thioredoxin reductase 1 / Txnrd1","entity_type_key":"protein"},"object":{"id":"acb6f128-e816-5d81-babc-db2ecbe93328","slug":"txn1","display_name":"TXN1","entity_type_key":"protein"},"evidence_count":1,"mechanism_event":{"id":"7dee368e-4243-5930-87b9-7381dce18356","stable_key":"548ab9d6-3a9b-5bed-879c-17d03813b636:b2-txnrd1-terminal-relay-event","event_type":"biochemical_relationship","label":"A second redox center carries electrons onward to thioredoxin.","description":"A rat TXNRD1 structure and docking model with human thioredoxin support a relay through the opposite subunit and C-terminal tail toward the substrate.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"e2cd7179-f218-54e8-9ce9-7a836ae35fac","slug":"fad","display_name":"FAD","entity_type_key":"small_molecule"},"role":"upstream cofactor","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"acb6f128-e816-5d81-babc-db2ecbe93328","slug":"txn1","display_name":"TXN1","entity_type_key":"protein"},"role":"human docking partner in Fig 6; model rather than measured turnover","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"dc89d7e2-8f89-577b-838f-42bf5d8ec7c8","slug":"selenium","display_name":"Selenium","entity_type_key":"nutrient_element"},"role":"nutrient incorporated into wild-type enzyme selenocysteine; not a freely bound ion","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""},{"entity":{"id":"44c93642-76cb-5254-9edb-14a3020a5ae6","slug":"rat-txnrd1","display_name":"Rat thioredoxin reductase 1 / Txnrd1","entity_type_key":"protein"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":3,"notes":""}]},"contexts":[{"dimension":"cross_nutrient","value_text":"B2-dependent electron input and selenium-containing terminal chemistry are separate serial steps.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"evidence_location","value_text":"Abstract","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Rat TXNRD1 Sec498Cys recombinant mutant with NADP+, 3.0-A crystallography and substrate-docking interpretation.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"exposure","value_text":"Purified-enzyme assay","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Human thioredoxin was docked onto the rat Sec498Cys structure (Fig 6); the complex and cross-species turnover were not measured.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Riboflavin research collection; topical membership is not evidence of a direct dietary effect.","comparator":null,"unit":null,"notes":"","entity":{"slug":"riboflavin","display_name":"Riboflavin (vitamin B2)","entity_type_key":"small_molecule"}},{"dimension":"organism","value_text":"Rattus norvegicus reductase and Homo sapiens thioredoxin docking partner","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"A second redox center carries electrons onward to thioredoxin.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[sandalova2001] Three-dimensional structure of a mammalian thioredoxin reductase: implications for mechanism and evolution of a selenocysteine-dependent enzyme. (2001). https://pubmed.ncbi.nlm.nih.gov/11481439/ DOI: 10.1073/pnas.171178698","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Purified recombinant enzyme; no intact tissue","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"561e7d35-34e9-5b12-967f-6e89e3aac15e","evidence_kind":"source_excerpt","locator":"Lines 1360-1372","start_line":1360,"end_line":1372,"excerpt":"### b2-txnrd1-terminal-relay\nA rat TXNRD1 structure and docking model with human thioredoxin support a relay through the opposite subunit and C-terminal tail toward the substrate.\nCondition category: normal\nnutrient_topic: Riboflavin research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: A second redox center carries electrons onward to thioredoxin.\norganism: Rattus norvegicus reductase and Homo sapiens thioredoxin docking partner\ntissue_or_cell_type: Purified recombinant enzyme; no intact tissue\nexperimental_model: Rat TXNRD1 Sec498Cys recombinant mutant with NADP+, 3.0-A crystallography and substrate-docking interpretation.\nlimitations: Human thioredoxin was docked onto the rat Sec498Cys structure (Fig 6); the complex and cross-species turnover were not measured.\nexposure: Purified-enzyme assay\ncross_nutrient: B2-dependent electron input and selenium-containing terminal chemistry are separate serial steps.\nevidence_location: Abstract\n[sandalova2001] Three-dimensional structure of a mammalian thioredoxin reductase: implications for mechanism and evolution of a selenocysteine-dependent enzyme. (2001). https://pubmed.ncbi.nlm.nih.gov/11481439/ DOI: 10.1073/pnas.171178698","model_system":"Rat TXNRD1 Sec498Cys recombinant mutant with NADP+, 3.0-A crystallography and substrate-docking interpretation.","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [sandalova2001] Three-dimensional structure of a mammalian thioredoxin reductase: implications for mechanism and evolution of a selenocysteine-dependent enzyme. 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