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C-terminal, alpha helical domain of Class Tau Glutathione S-transferases Glutathione S-transferase (GST) C-terminal domain family, Class Tau 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 plant-specific class Tau GST subfamily has undergone extensive gene duplication. The Arabidopsis and Oryza genomes contain 28 and 40 Tau GSTs, respectively. They are primarily responsible for herbicide detoxification together with class Phi GSTs, showing class specificity in substrate preference. Tau enzymes are highly efficient in detoxifying diphenylether and aryloxyphenoxypropionate herbicides. In addition, Tau GSTs play important roles in intracellular signalling, biosynthesis of anthocyanin, responses to soil stresses and responses to auxin and cytokinin hormones.
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