Plant glutathione transferases — a decade falls short

The glutathione transferase (GST) superfamily in plants has been subdivided into eight classes, seven of which (phi, tau, zeta, theta, lambda, dehydroascorbate reductase, and tetrachlorohydroquinone dehalogenase) are soluble and one is microsomal. Since their identification in plants in 1970, these enzymes have been well established as phase II detoxification enzymes that perform several other essential functions in plant growth and development. These enzymes catalyze nucleophilic conjugation of the reduced form of the tripeptide glutathione to a wide variety of hydrophobic, electrophilic, and usually cytotoxic substrates. In plants, the conjugated product is either sequestered in the vacuole or transferred to the apoplast. The GSTs of phi and tau classes, which are plant-specific and the most abundant, are chiefly involved in xenobiotic metabolism. Zeta- and theta-class GSTs have very restricted activities towards xenobiotics. Theta-class GSTs are glutathione peroxidases and are involved in oxidative-str...