{"id":"9db93a81-9981-55a3-ae15-47a3db2b0a7d","stable_key":"research:dio2-t4-to-t3","predicate":"deiodinates_to_produce","statement":"DIO2 catalyzes outer-ring deiodination of T4 to T3 in functional enzyme-expression experiments.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"literature_reviewed:direct_experimental","direction":"positive","is_public":true,"mechanism_event_id":"4181f4c2-ffcf-5985-a886-f1d5558e0edb","mechanism_event_label":"DIO2 converts T4 into the active thyroid hormone T3.","subject":{"id":"fc93f0af-2123-58b6-bb7a-ff800479799a","slug":"dio2","display_name":"DIO2","entity_type_key":"protein"},"object":{"id":"559f37d2-ee0a-589b-8689-fa80ca9ae653","slug":"triiodothyronine","display_name":"T3","entity_type_key":"small_molecule"},"evidence_count":1,"mechanism_event":{"id":"4181f4c2-ffcf-5985-a886-f1d5558e0edb","stable_key":"research:dio2-t4-to-t3","event_type":"experimentally_scoped_interaction","label":"DIO2 converts T4 into the active thyroid hormone T3.","description":"DIO2 catalyzes outer-ring deiodination of T4 to T3 in functional enzyme-expression experiments.","status":"active","compartment":null,"participants":[{"entity":{"id":"fc93f0af-2123-58b6-bb7a-ff800479799a","slug":"dio2","display_name":"DIO2","entity_type_key":"protein"},"role":"catalyst","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"559f37d2-ee0a-589b-8689-fa80ca9ae653","slug":"triiodothyronine","display_name":"T3","entity_type_key":"small_molecule"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"f2b25f38-ec94-57d0-a46d-dd0fee45f01e","slug":"thyroxine","display_name":"T4","entity_type_key":"small_molecule"},"role":"substrate","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""}]},"contexts":[{"dimension":"experimental_model","value_text":"Rat and human DIO2 cDNA characterization and functional expression.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"This reaction alone cannot diagnose hidden tissue hypothyroidism from normal blood tests or quantify benefit from selenium intake.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"organism","value_text":"Human and rat","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"ee4dd84b-b027-5dcf-aba8-f74ed0b921fb","evidence_kind":"curated_literature_summary","locator":"lines 1009-1018","start_line":1009,"end_line":1018,"excerpt":"## dio2-t4-to-t3\n\nDIO2 converts T4 into the active thyroid hormone T3.\n\nDIO2 catalyzes outer-ring deiodination of T4 to T3 in functional enzyme-expression experiments.\n\nExperimental model: Rat and human DIO2 cDNA characterization and functional expression.\nOrganism: Human and rat\nLimitations: This reaction alone cannot diagnose hidden tissue hypothyroidism from normal blood tests or quantify benefit from selenium intake.\nPrimary reference: [Cloning of the mammalian type II iodothyronine deiodinase](https://www.jci.org/articles/view/118806)","model_system":"Rat and human DIO2 cDNA characterization and functional expression.","directness":"author_interpretation","verification_status":"secondary_verified","notes":"Curated summary; inspect the linked primary papers for original methods and results.","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"4f892f13-06ea-5199-a33c-a703f35c80ae","stable_key":"selenium-research-2026-09-17","title":"Selenium: literature corrections and mechanism additions","document_type":"curated_literature_review","citation_label":"Metabolic Ledger literature curation, 17 September 2026; primary papers linked individually","file_path":"","sha256":"0b818b10c1c7120e5caf7f4d4019d7bd025d745692e424f515d3ef903c9ab7f3","revision_id":"80984e03-5f0f-5877-8094-afef7637444e","review_status":"secondary_verified","notes":"Secondary curated summaries of primary experiments, with explicit models and limitations. Not archived primary full text."}}],"relations":[],"conflicts":[],"corrections":[],"research":{"topic":"Thyroid hormone processing","plain_language":"DIO2 converts T4 into the active thyroid hormone T3.","evidence_scope":"direct_experimental","papers":[{"key":"catalog-dio2-1996","title":"Cloning of the mammalian type II iodothyronine deiodinase","url":"https://www.jci.org/articles/view/118806","doi":"10.1172/JCI118806","year":1996,"model":"Rat and human DIO2 cDNA characterization and functional expression.","summary":"Identifies a distinct selenoenzyme that converts thyroxine into T3; tissue expression varies."}]}}