Glutathione peroxidase (GPx) enzymes are generally selenium-containing tetrameric glycoproteins that help prevent lipid peroxidation of cell membranes. This protein is one of only a few proteins known in higher vertebrates to contain selenocysteine, which occurs at the active site of glutathione peroxidase and is coded by UGA, that normally functions as a translation termination codon. There are eight GPx homologs (GPx-1–8). GPx-1 plays an important role in the antioxidant defense of the vascular wall and neural cells in response to oxidative stress.
