iodothyronine deiodinase type 3 (DIO3 ITDI3 TXDI3)

Function

• responsible for deiodination of T4 into reverse-T3 & of T3 into T2 (3,3'-diiodothyronine)
• may play a role in preventing premature exposure of developing fetal tissues to adult levels of thyroid hormones
• can regulate circulating fetal thyroid hormone concentrations throughout gestation
• essential role for regulation of thyroid hormone inactivation during embryological development

3,3',5'-triiodo-L-thyronine + iodide + A + H+
         <-->
L-thyroxine + AH(2)

Kinetic parameters:

• Kcat/Km ratio for 5-deiodination of T3 is > 1000-fold that of 5'-deiodination of reverse T3

Structure

belongs to the iodothyronine deiodinase family

Compartment

cell membrane, endosome membrane

Expression

expressed in placenta & several fetal tissues

More general terms

• iodothyronine deiodinase

Additional terms

• thyrosine/iodothyronine [T4] deiodinase, iodide peroxidase or T3 synthase

Database

• Kegg: http://www.genome.jp/dbget-bin/www_bget?hsa:1735
• OMIM: https://mirror.omim.org/entry/601038
• UniProt: http://www.uniprot.org/uniprot/P55073.html