Glutamine synthase

Glutamine synthetase (GS) is an enzyme that catalyzes the synthesis of glutamine from glutamate and ammonia. Glutamine is an important amino acid that serves as a nitrogen donor for the biosynthesis of other molecules, such as nucleotides and amino acids. Glutamine synthetase also plays a role in detoxifying ammonia, which is toxic to cells. Glutamine synthetase is found in both plants and animals, and has different functions depending on the tissue and organism. In humans, glutamine synthetase is mainly expressed in astrocytes, where it regulates the glutamate-glutamine cycle and protects neurons from excitotoxicity.