Glutamate Decarboxylase 2 (GAD2)

Glutamate decarboxylase (GAD) is an enzyme that catalyzes the decarboxylation of glutamate to GABA and CO2. GAD uses PLP as a cofactor. In mammals, GAD exists in two isoforms encoded by two different genes - Gad1 and Gad2. These isoforms are GAD67 and GAD65 with molecular weights of 67 and 65 kDa, respectively. GAD1 and GAD2 are expressed in the brain where GABA is used as a neurotransmitter, GAD2 is also expressed in the pancreas. GAD65 is an enzyme that is produced primarily by pancreatic islet cells. A number of recent studies indicate that patients with insulin-dependent diabetes mellitus (IDDM) often have antibodies to GAD65 and several other islet cell antigens.Both GAD67 and GAD65 are targets of autoantibodies in people who later develop insulin-dependent diabetes mellitus 0.312-20 ng/mL