Iodotyrosine deiodinase 1 (IYD)

Iodotyrosine deiodinase 1 (IYD) is an FMN-dependent enzyme present on the apical membrane of thyroid follicular cells and is essential for iodide salvage during thyroid hormone biosynthesis. IYD catalyzes reductive deiodination of mono- and diiodotyrosine, byproducts of thyroglobulin hydrolysis, releasing iodide for reutilization in new hormone synthesis. This process helps maintain both iodide and thyroid hormone levels, supporting metabolic rate, protein expression, and temperature regulation. IYD is a membrane-bound flavoprotein belonging to the nitroreductase superfamily and forms a functional dimer with active site lid domains that sequester and stabilize substrate interactions. Genetic deficiency or mutations in IYD lead to loss of enzyme activity, ineffective iodide salvage, and various thyroid-related diseases including hypothyroidism and developmental impairment. Diagnosis of its deficiency is possible by measuring elevated levels of iodotyrosine derivatives in blood and urine, making it useful as a biomarker for congenital hypothyroidism. There are currently no approved drugs specifically targeting IYD, but its unique structure and catalytic mechanism make it a promising candidate for biotechnological or therapeutic development.

Other names

Iodotyrosine deiodinaseIYDiodotyrosine dehalogenase 1DEHAL1C6orf71IYD-1TDH4dJ422F24.1

Reductive deiodination: catalyzes removal of iodine from mono- and diiodotyrosine using NADPH and FMN as a cofactor