GGT7 Gene: Function, Expression, and Disease Associations | Gamma-Glutamyltransferase 7

GGT7 (Gamma-glutamyltransferase 7) is a member of the gamma-glutamyltransferase (GGT) family, which catalyzes the transfer of gamma-glutamyl groups from glutathione and other gamma-glutamyl compounds to acceptors. This enzyme plays a critical role in glutathione metabolism, maintaining cellular redox balance, and protecting cells against oxidative stress. GGT7 is a type II transmembrane protein localized to the plasma membrane and is expressed in various tissues, with notable expression in the kidney, liver, and pancreas. The gene spans approximately 20 kb on chromosome 20q11.22 and encodes multiple transcript variants. GGT7 has been implicated in several physiological and pathological processes, including detoxification, amino acid transport, and potentially in cancer biology, where its expression may influence tumor progression and drug resistance.

Tissue Expression

Cell Line Expression

Hotspot Mutations

Mutation functional classification

• Glutathione metabolism (Reactome: R-HSA-174403)

• Metabolism of amino acids and derivatives (Reactome: R-HSA-71291)

• Phase II - Conjugation of compounds (Reactome: R-HSA-156580)

The GGT7 protein is a type II transmembrane glycoprotein composed of 602 amino acids. It is synthesized as a single-chain precursor that is proteolytically cleaved into a large and a small subunit, which remain associated to form the active enzyme. The protein localizes to the plasma membrane, with its active site facing the extracellular space. GGT7 catalyzes the hydrolysis of gamma-glutamyl bonds in glutathione and other gamma-glutamyl compounds, initiating their degradation and facilitating the recycling of cysteine, a rate-limiting substrate for glutathione synthesis. This activity is crucial for maintaining intracellular glutathione levels and protecting cells from oxidative damage. The enzyme is expressed in a tissue-specific manner, with highest levels in the kidney, where it participates in the metabolism of glutathione filtered by the glomeruli. Post-translational modifications include N-glycosylation, which is essential for proper folding and enzymatic activity.