Iodothyronine deiodinase

T3, through binding a nuclear thyroid hormone receptor, influences the expression of genes in practically every vertebrate cell.

In tissues, deiodinases can either activate or inactivate thyroid hormones: The major part of thyroxine deiodination occurs within the cells.

[citation needed] The three deiodinase enzymes share certain structural features in common although their sequence identity is lower than 50%.

[7] Deiodinases are dimeric integral membrane proteins with single transmembrane segments and large globular heads (see below).

[9] They share a TRX fold that contains the active site including the rare selenocysteine amino acid and two histidine residues.

[12] Also, iodothyronine deiodinases (type 2 y 3; DIO2 and DIO3, respectively) respond to seasonal changes in photoperiod-driven melatonin secretion and govern peri-hypothalamic catabolism of the prohormone thyroxine (T4).

However, during the adaptation to reproductively inhibitory photoperiods, the levels of T3 decrease due to peri-hypothalamic DIO3 expression that catabolizes T4 and T3 into receptor inactive amines.

[21] During development, hypothyroidism is considered more severe and leads to neurotoxicity as cretinism or other human cognitive disorders,[22] altered metabolism and underdeveloped organs.

The drug iopanoic acid (IOP) decreased cutaneous cell proliferation by inhibition of deiodinase enzyme type 1 or 2 reducing the conversion of T4 to T3.

The environmental chemical DE-71, a PBDE pentaBDE brominated flame retardant decreased hepatic deiodinase I transcription and enzyme activity in neonatal rats with hypothyroidism.