Type I iodothyronine deiodinase (DIO1) (DIO1)

Type I iodothyronine deiodinase (DIO1) is a membrane-bound selenoprotein primarily expressed in the liver, kidney, and thyroid gland (UniProt: P41222). It serves as a key regulator of thyroid hormone activity by catalyzing the 5'-deiodination of thyroxine (T4) to produce the active hormone triiodothyronine (T3), as well as the 5-deiodination of T4 to produce reverse T3 (rT3) (PubMed: 11396613). DIO1 is distinct from other deiodinases due to its high catalytic efficiency for rT3 and its specific inhibition by the thioureylene drug propylthiouracil (PTU) (StatPearls: NBK545206). In pathological states such as hyperthyroidism or thyroid storm, DIO1 activity is often upregulated, making it a therapeutic target for drugs that aim to rapidly lower systemic T3 levels (PubMed: 15531501). Conversely, its activity can be suppressed by certain medications like amiodarone and systemic illnesses, leading to non-thyroidal illness syndrome (PubMed: 19035356). Understanding DIO1 function is vital for optimizing thyroid replacement therapies and managing endocrine disorders where peripheral hormone conversion is a factor.

Other names

Type 1 deiodinaseIodothyronine 5'-deiodinase type 15'-deiodinase type ID1Deiodinase type I

Inhibition of the enzyme's catalytic activity to reduce the peripheral conversion of the prohormone thyroxine (T4) into the more potent active hormone triiodothyronine (T3) (StatPearls: NBK545206).