Frontiers Gamma glutamyl cycle in plants: a bridge connecting the environment to the plant cell? How Do Cells Produce Glutathione? Glutathione Reporter Crystal structures of glutamyltranspeptidase from Escherichia coli, a key enzyme in glutathione metabolism, and its reaction intermediate PNAS Gamma glutamyl transferase (GGT), Glutamyl Transpeptidase 8 But none of this explains WHY GGT is elevated at all 1GGT is maintaining glutathione stores 2If glutathione is, GGT goes 3No GGT? glutathione Q: What depletes glutathione? A: oxidative stress The Emerging Roles of Glutamyl Peptides Produced by Glutamyltransferase and the Glutathione Synthesis System