Catalyzes the conjugation of glutathione to a large variety of electrophilic compounds. glutathione + RX = a halide anion + an S-substituted glutathione + H(+) Homodimer or heterodimer of GSTA1 and GSTA2. In addition to its enzymatic activity, the homodimer of Ya chains, called ligandin, binds various organic anions, xenobiotics, and azocarcinogen dyes. Belongs to the GST superfamily. Alpha family.