Enables 4-aminobutyrate transaminase activity. Involved in several processes, including gamma-aminobutyric acid biosynthetic process; positive regulation of inhibitory postsynaptic potential; and regulation of secretion. Located in mitochondrial matrix and neuron projection. Used to study several diseases, including Huntington's disease; epilepsy (multiple); heroin dependence; ischemia; and mental depression. Biomarker of Parkinsonism. Human ortholog(s) of this gene implicated in Alzheimer's disease; GABA aminotransferase deficiency; and Huntington's disease. Orthologous to human ABAT (4-aminobutyrate aminotransferase). [provided by Alliance of Genome Resources, Apr 2022]