May play a role in protecting plants from some xenobiotic chemicals by degrading vacuolar glutathione conjugates into cysteine conjugates. an alpha-amino acid + an N-terminal (5-L-glutamyl)-[peptide] = 5-L-glutamyl amino acid + N-terminal L-alpha-aminoacyl-[peptide] glutathione + H2O = L-cysteinylglycine + L-glutamate an S-substituted glutathione + H2O = an S-substituted L-cysteinylglycine + L-glutamate Sulfur metabolism; glutathione metabolism. Expressed in roots, cotyledons, leaves, flowers and siliques. By auxin. No visible phenotype under normal growth conditions. Belongs to the gamma-glutamyltransferase family.