This is a bifunctional protein that also has the activity of EC?2.3.2.2, ¦Ã-glutamyltransferase. The enzyme binds its substrate by forming an initial ¦Ã-glutamyl-enzyme intermediate, releasing the?L-cysteinylglycine part of the molecule. The enzyme then reacts with either a water molecule or a different acceptor substrate (usually an?L-amino acid or a dipeptide) to form?L-glutamate or a product containing a new ¦Ã-glutamyl isopeptide bond, respectively. The enzyme acts on glutathione, glutathione-S-conjugates, and, at a lower level, on other substrates with an N-terminal?L-¦Ã-glutamyl residue. It plays a crucial part in the glutathione-mediated xenobiotic detoxification pathway. The enzyme consists of two chains that are created by the proteolytic cleavage of a single precursor polypeptide.
