Conjugation of reduced glutathione to a wide number of exogenous and endogenous hydrophobic electrophiles. Also binds steroids, bilirubin, carcinogens and numerous organic anions. Has dichloromethane dehalogenase activity. glutathione + RX = a halide anion + an S-substituted glutathione + H(+) Homodimer. In liver, highest expression found in central vein limiting plate hepatocytes. In lung, expressed mainly in Clara cells of the bronchiolar epithelium and, at low levels, in type II alveolar cells. Belongs to the GST superfamily. Theta family.