Glutathione peroxidase; Iodothyronine deiodinase; Thioredoxin reductase (GPx; DIO (or ID, for deiodinase, context-dependent); TrxR)

Glutathione peroxidase, iodothyronine deiodinase, and thioredoxin reductase are distinct families of selenoprotein enzymes essential for cellular redox regulation and metabolic homeostasis. Glutathione peroxidase enzymes (GPx) reduce hydrogen peroxide and lipid hydroperoxides to water or alcohols, protecting cells from oxidative damage. Iodothyronine deiodinases (DIO1/2/3) catalyze the activation and inactivation of thyroid hormones, governing local and systemic thyroid hormone levels. Thioredoxin reductases (TrxR) regenerate reduced thioredoxin, supporting cellular antioxidant systems and redox signaling. All three enzyme families are dependent on the trace element selenium within their active sites as selenocysteine residues, and impairment in their activity is linked to various diseases, including cancer, neurodegeneration, cardiovascular, and thyroid disorders.

Other names

GPxGlutathione peroxidase 1/2/3/4/6/7/8 depending on isoformDIO1DIO2DIO3Type I/II/III iodothyronine deiodinaseThyroxine 5'-deiodinaseTrxRTXNRD1/2/3NADPH-dependent thioredoxin reductase

Inhibition (e.g., auranofin inhibits thioredoxin reductase, leading to increased oxidative stress in cancer cells). Selenium supplementation (boosts selenoenzymes' activity). Thyroid hormone regulation (for deiodinase-targeted drugs).