Glutamine Synthetase [MD285]

Glutamine synthetase, an enzyme that catalyzes the amination of glutamic acid to form glutamine, is found in mammals as an octamer of eight identical 45 kDa subunits. Glutamine synthetase activity has been shown to be a useful marker of astrocytes and an important differentiation feature in retina. Glutamine synthetase is also present in hepatocytes near the hepatic central veins. In liver focal nodular hyperplasia (FNH), the glutamine synthetase immunohistochemical staining pattern appears map-like, which is useful in differentiating FNH from normal liver tissue or other hepatic mass lesions.