Conjugation of reduced glutathione to a wide number of exogenous and endogenous hydrophobic electrophiles. May govern uptake and detoxification of both endogenous compounds and xenobiotics at the testis and brain blood barriers. glutathione + RX = a halide anion + an S-substituted glutathione + H(+) Homodimer. Testis and brain. The N-terminus is blocked. Belongs to the GST superfamily. Mu family.