Conjugation of reduced glutathione to a wide number of exogenous and endogenous hydrophobic electrophiles. glutathione + RX = a halide anion + an S-substituted glutathione + H(+) Homodimer. Expressed in liver, stomach and small intestine. Not expressed in spleen, kidney, colon, heart, muscle, brain or lung. Belongs to the GST superfamily. Mu family.