GLUL(Glutamine synthetase) is also named as GS,GLNS and belongs to the glutamine synthetase family.This enzyme has 2 functions: it catalyzes the production of glutamine and 4-aminobutanoate (gamma-aminobutyric acid,GABA),the latter in a pyridoxal phosphate-independent manner By similarity. Essential for proliferation of fetal skin fibroblasts.Defects in GLUL are the cause of congenital systemic glutamine deficiency (CSGD).Organismal glutamine production is augmented secondary to an increase in the activity of glutamine synthetase in the lung and skeletal muscle. There are other bands with higher (66 kDa,97 kDa) and lower (30 kDa)molecular weights also detected besides the 42 kDa band indicating the proteolysis of GLUL protein by the ubiquitin system.