Gamma-glutamyltransferase 7Gamma-glutamyltransferase 7 is an enzyme that in humans is encoded by the GGT7 gene.FunctionGamma-glutamyltransferase is a membrane-associated protein involved in both glutathione metabolism and the transpeptidation of amino acids. Changes in gamma-glutamyltransferase activity may signal preneoplastic or toxic conditions in the liver or kidney. The protein encoded by this gene is similar in sequence to gamma-glutamyltransferase, but its function is unknown.