Glutamine Synthetase reglutes intracellular concentration of glutamate. Glutamine Synthetase catalyzes the synthesis of glutamine from glutamate and ammonia. Glutamine is an important source of energy and that takes part in cell prolifetation, inhibition of apoptosis, and cell signaling. Glutamine Synthetase is expressed during early fetal stages, and has a role in maintaining body PH by removing ammonia from circulation. Mutations in the GLUL gene are related to congenital glutamine deficiency.