GGT1 belongs to the gamma-glutamyltransferase protein family. Many members of this family have not yet been fully characterized and some of which may represent pseudogenes. GGT1 is composed of a heavy chain and a light chain. It catalyzes the transfer of the glutamyl moiety of glutathione to a variety of amino acids and dipeptide acceptors. GGT1 also initiates extracellular glutathione (GSH) breakdown, provides cells with a local cysteine supply and contributes to maintain intracelular GSH level. As part of the cell antioxidant defense mechanism, GGT1 can be detected in fetal and adult kidney and liver, adult pancreas, stomach, intestine, placenta and lung. Defects in GGT1 can cause glutathionuria which is known as an autosomal recessive disease.
