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 (By similarity). Interacts with PFKM isoform 2 and isoform 3 (via N-terminal testis-specific region) (PubMed:19889946). Belongs to the GST superfamily. Mu family.