GABA and 2-oxoglutarate (2OG) are converted to succinate semialdehyde (SUCCSA) and L-glutamate (L-Glu) by 4 aminobutyrate aminotransferase (ABAT). The reaction takes place in the mitochondrial matrix. The active form of the enzyme is a dimer, with each subunit associated with a molecule of pyridoxal phosphate (PXLP) (De Biase et al. 1995).