GABA degradation pathways exists in almost all eukaryotic organisms and takes place by the action of similar enzymes. Although, GABA in E.coli is predominantly used as an alternative source of energy through GABA degradation pathways, GABA in higher eukaryotic organisms acts as an inhibitory neurotransmitter and also as regulator of muscle tone. GABA degradation pathways in eukaryotes are responsible for the inactivation of GABA.