Conjugation of reduced glutathione to a wide number of exogenous and endogenous hydrophobic electrophiles. Involved in the formation of glutathione conjugates of both prostaglandin A2 (PGA2) and prostaglandin J2 (PGJ2) (PubMed:9084911). Participates in the formation of novel hepoxilin regioisomers (PubMed:21046276). Regulates negatively CDK5 activity via p25/p35 translocation to prevent neurodegeneration. glutathione + RX = a halide anion + an S-substituted glutathione + H(+) glutathione + prostaglandin J2 = prostaglandin J2-S-(R)-glutathione glutathione + prostaglandin J2 = prostaglandin J2-S-(S)-glutathione glutathione + prostaglandin A2 = prostaglandin A2-S-(S)-glutathione 11(S)-hydroxy-14(S),15(S)-epoxy-(5Z,8Z,12E)-eicosatrienoate + glutathione = (11S,15S)-dihydroxy-14(R)-S-glutathionyl-(5Z,8Z,12E)-eicosatrienoate Homodimer. Interacts with CDK5. The 83 N-terminal amino acids function as un uncleaved transit peptide, and arginine residues within it are crucial for mitochondrial localization. Belongs to the GST superfamily. Pi family.