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.