DIO1
DIO1 (iodothyronine deiodinase 1, also known as TXDI1) is a selenoprotein enzyme that activates and inactivates thyroid hormones by removing iodine atoms from the outer or inner ring. It supplies most of the circulating 3,5,3'-triiodothyronine (T3) in vertebrates. Browse Assay Genie's current range of DIO1 research reagents below, or read on for the biology behind the target.
DIO1 plays a central role in thyroid hormone (TH) metabolism, with specific roles in both TH activation and inactivation. By outer-ring deiodination it converts the prohormone L-thyroxine (T4), secreted by the thyroid gland, into the bioactive hormone T3. It also converts 3,3',5'-triiodothyronine (rT3) to 3,3'-diiodothyronine and 3',5'-diiodothyronine to 3'-monoiodothyronine. By inner-ring deiodination it converts T4 to rT3 and T3 to 3,3'-diiodothyronine, and it also acts on 3,5-diiodothyronine and 3,3'-diiodothyronine.
The substrate range extends beyond the classic iodothyronines. DIO1 catalyses phenolic and tyrosyl ring deiodinations of several iodothyronamines, and it deiodinates sulfated forms of T4 and T3. The protein is annotated at the cell membrane, the endoplasmic reticulum membrane and the basolateral cell membrane. The DIO1 protein provides most of the circulating T3, which is essential for growth, differentiation and basal metabolism in vertebrates.
The DIO1 gene encodes a member of the iodothyronine deiodinase family, a group within the HGNC selenoprotein gene group. Its active site contains the rare amino acid selenocysteine (Sec), which is encoded by a UGA codon that normally signals translation termination. A Sec insertion sequence (SECIS) stem-loop in the 3' UTR of selenoprotein mRNAs lets the ribosome read UGA as Sec rather than as a stop signal. Alternatively spliced transcript variants have been reported. Previous names include deiodinase, iodothyronine, type I. Mouse and rat both have a Dio1 ortholog, and DIO2 and DIO3 are related deiodinases.
DIO1 converts T4 to T3 and inactivates thyroid hormones, so it is a key enzyme for studying how hormone activity is regulated.
Its active-site selenocysteine and reliance on a SECIS element make DIO1 a useful model for selenocysteine incorporation and recoding of the UGA codon.
DIO1 provides most circulating T3, which is essential for growth, differentiation and basal metabolism in vertebrates.
DIO1 acts on iodothyronines, iodothyronamines and sulfated derivatives through outer- and inner-ring deiodination, supporting work on deiodination routes.
DIO1 catalyses deiodination of thyroid hormones and related compounds. By outer-ring deiodination it activates the prohormone T4 to T3, and by inner-ring deiodination it inactivates thyroid hormones, for example converting T4 to rT3 and T3 to 3,3'-T2. It provides most of the circulating T3.
The HGNC name is iodothyronine deiodinase 1, and UniProt calls the protein type I iodothyronine deiodinase. TXDI1 is an alias, and a previous name is deiodinase, iodothyronine, type I. The gene produces alternatively spliced transcript variants.
DIO1 contains selenocysteine at its active site. This amino acid is encoded by a UGA codon, which normally signals termination. A SECIS stem-loop in the 3' UTR of the mRNA allows UGA to be read as selenocysteine. Mouse and rat have a Dio1 ortholog; check the datasheet of any product for its validated reactivity.
Other iodothyronine deiodinase family members involved in thyroid hormone activation and inactivation, with products at Assay Genie.
Gene and protein annotations from HGNC, NCBI Gene and UniProt P49895; product specifications from Assay Genie datasheets.