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C-terminal, alpha helical domain of Class Alpha Glutathione S-transferases Glutathione S-transferase (GST) C-terminal domain family, Class Alpha subfamily; GSTs are cytosolic dimeric proteins involved in cellular detoxification by catalyzing the conjugation of glutathione (GSH) with a wide range of endogenous and xenobiotic alkylating agents, including carcinogens, therapeutic drugs, environmental toxins, and products of oxidative stress. The GST fold contains an N-terminal thioredoxin-fold domain and a C-terminal alpha helical domain, with an active site located in a cleft between the two domains. GSH binds to the N-terminal domain while the hydrophobic substrate occupies a pocket in the C-terminal domain. The class Alpha subfamily is composed of vertebrate GSTs which can form homodimer and heterodimers. There are at least six types of class Alpha GST subunits in rats, four of which have human counterparts, resulting in many possible isoenzymes with different activities, tissue distribution and substrate specificities. Human GSTA1-1 and GSTA2-2 show high GSH peroxidase activity. GSTA3-3 catalyzes the isomerization of intermediates in steroid hormone biosynthesis. GSTA4-4 preferentially catalyzes the GSH conjugation of alkenals.
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