The function of Ensembl gene identifier ENSG00000128683 (GAD1, glutamate decarboxylase 1) is as follows. Catalyzes the synthesis of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) with pyridoxal 5'-phosphate as cofactor. . [Isoform 3]: Enzymatically inactive as glutamate decarboxylase. .