Catalyzes the conjugation of glutathione to a large variety of electrophilic compounds. glutathione + RX = a halide anion + an S-substituted glutathione + H(+) Homodimer (PubMed:12549910). Heterodimer of GSTA1 and GSTA2 (By similarity). Expressed in the kidney. Belongs to the GST superfamily. Alpha family.