Gamma-glutamyltransferase

Structure of Gamma-Glutamyltransferase

Gamma-Glutamyltransferase (GGT) is an enzyme that plays a crucial role in the gamma-glutamyl cycle, which is involved in the metabolism of glutathione and the transfer of amino acids across the cellular membrane. GGT is found in many tissues throughout the body, with particularly high concentrations in the liver, kidney, and pancreas.

Function

GGT is primarily responsible for the transfer of the gamma-glutamyl functional group from molecules such as glutathione to an acceptor, which may be an amino acid, a peptide, or water. This process is essential for the breakdown and resynthesis of glutathione, a critical antioxidant that protects cells from oxidative damage.

Clinical Significance

GGT levels are commonly measured in blood tests as a marker of liver function. Elevated levels of GGT can indicate liver disease, bile duct obstruction, or alcohol abuse. It is often used in conjunction with other liver enzymes, such as alanine transaminase (ALT) and aspartate transaminase (AST), to assess liver health.

Structure

The structure of GGT is characterized by its ability to bind to the gamma-glutamyl moiety of glutathione. The enzyme is a membrane-bound glycoprotein, and its active site is located on the extracellular side of the membrane. The image on the right shows the detailed structure of GGT, highlighting its active site and binding domains.

Related Pages

• Glutathione
• Liver function tests
• Enzyme
• Oxidative stress