The protein encoded by this gene is an enzyme that catalyzes the production of gamma-aminobutyric acid from L-glutamic acid. Alternative splicing of this gene results in three products, the predominant 67 kDa isoform, a smaller 25 kDa isoform, and an even smaller 49 aa isoform. The two shorter isoforms are not thought to retain catalytic activity. [provided by RefSeq, Apr 2023]