dio3b - iodothyronine deiodinase 3b

The protein encoded by this gene belongs to the iodothyronine deiodinase family. It catalyzes the inactivation of thyroid hormone by inner ring deiodination of the prohormone thyroxine (T4) and the bioactive hormone 3,3',5-triiodothyronine (T3) to inactive metabolites, 3,3',5'-triiodothyronine (RT3) and 3,3'-diiodothyronine (T2), respectively. Two paralogs of this gene have been identified in zebrafish on chromosomes 17 and 20. Both encode enzymatically active proteins; however, their gene structure and tissue expression patterns are markedly different. This gene is unique in that it has 2 exons compared to orthologs in all other vertebrate species studied to date, which are intronless. Knockdown of this gene causes severe microsomia, indicating that this gene is critical for the determination fetal size during early embryonic development. This protein is a selenoprotein, containing the rare selenocysteine (Sec) amino acid at its active site. Sec is encoded by the UGA codon, which normally signals translation termination. The 3' UTRs of selenoprotein mRNAs contain a conserved stem-loop structure, designated the Sec insertion sequence (SECIS) element, that is necessary for the recognition of UGA as a Sec codon rather than as a stop signal. [provided by RefSeq, Jul 2017]

NCBI Orthologs

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