The γ-Glutamyl Cycle: A Possible Transport System for Amino Acids

This is the authors' abstract. We don't add key points for this paper.

Evidence is presented that rat kidney contains enzymes that catalyze the synthesis and utilization of glutathione; these reactions, which involve the uptake and release of amino acids from gamma-glutamyl linkage, constitute a cyclical process which is termed "the gamma-glutamyl cycle." The gamma-glutamyl cycle has properties that fulfill the requirements of an amino acid transport system. Thus, gamma-glutamyl transpeptidase may function in translocation and gamma-glutamylcysteine synthetase and glutathione synthetase may catalyze energy-requiring "recovery" steps in transport. These and other considerations suggest that glutathione serves a carrier function in amino acid transport.