<p>This entry represents glutamate decarboxylase (Gad;<db_xref db="EC" dbkey=" 4.1.1.15"/>) it is a pyridoxal 5'-phosphate (PLP)-dependent enzyme, which catalyses the irreversible alpha-decarboxylation of L-glutamate to gamma-aminobutyrate (GABA). This enzyme is widely distributed amongst eukaryotes and prokaryotes, but its function varies in different organisms [<cite idref="PUB00029912"/>].</p><p>GadD has a crucial role in the vertebrate central nervous system where it is responsible for the synthesis of GABA, the major inhibitory neurotransmitter. In the majority of vertebrates Gad occurs in two isoforms, Gad65 and Gad67, both active at neutral pH [<cite idref="PUB00034432"/>]. Gad isoforms (GadA and GadB) have also been reported in some bacterial species, including the Gram-negative bacterium [<cite idref="PUB00034433"/>] and Gram-positive bacterium [<cite idref="PUB00034434"/>].</p><p>A unique feature of plant and yeast Gad is the presence of a calmodulin (CaM)-binding domain in the C-terminal region. In <taxon tax_id="4932">Saccharomyces cerevisiae</taxon> (Baker's yeast), Gad expression is required for normal oxidative stress tolerance [<cite idref="PUB00034435"/>]. In plants, Gad is thought to be a stress-adapter chaperonin sensing Ca2+ signals.</p> Glutamate decarboxylase