Type I Iodothyronine Deiodinase (DIO1) Human Recombinant Protein

The protein encoded by this gene is a thiol-requiring propylthiouracil-sensitive oxidoreductase. It activates thyroid hormone by converting the prohormone thyroxine (T4) by outer ring deiodination (ORD) to bioactive 3,3',5-triiodothyronine (T3). It also degrades both hormones by inner ring deiodination (IRD). Alternative splicing results in multiple transcript variants encoding different isoforms. Some, but not all, isoforms contain a selenocysteine (Sec) residue encoded by the UGA codon, which normally signals translation termination. The 3' UTR of Sec-containing genes have a common stem-loop structure, the sec insertion sequence (SECIS), which is necessary for the recognition of UGA as a Sec codon rather than as a stop signal. Additional transcript variants have been described but are not supported by experimental evidence. [provided by RefSeq, Jul 2008]

DIO1: Responsible for the deiodination of T4 (3,5,3',5'- tetraiodothyronine) into T3 (3,5,3'-triiodothyronine) and of T3 into T2 (3,3'-diiodothyronine). Plays a role in providing a source of plasma T3 by deiodination of T4 in peripheral tissues such as liver and kidney. Belongs to the iodothyronine deiodinase family. 9 isoforms of the human protein are produced by alternative splicing.

Protein type: EC 1.97.1.10; Oxidoreductase; Membrane protein, integral

Chromosomal Location of Human Ortholog: 1p33-p32

Cellular Component: endoplasmic reticulum membrane; plasma membrane; integral to membrane

Molecular Function: thyroxine 5'-deiodinase activity; selenium binding

Biological Process: thyroid hormone generation; hormone biosynthetic process