Required for the degradation of gamma-aminobutyric acid (GABA), which is important for utilization of GABA as nitrogen source and for oxidative stress tolerance. Deaminates GABA to succinate semialdehyde, which in turn is converted to succinate by the succinate-semialdehyde dehydrogenase UGA2. Cannot transaminate beta-alanine (BAL). 2-oxoglutarate + 4-aminobutanoate = L-glutamate + succinate semialdehyde Optimum pH is 8.3. Homodimer and homotetramer. Subject to nitrogen catabolite repression. Expression is low in the presence of the preferred nitrogen sources, and up-regulated by GABA. Present with 573 molecules/cell in log phase SD medium. Belongs to the class-III pyridoxal-phosphate-dependent aminotransferase family.