Glutamate decarboxylase is an enzyme that plays a crucial role in the brain by converting glutamate, an excitatory neurotransmitter, into gamma-aminobutyric acid (GABA), which is an inhibitory neurotransmitter. This conversion helps regulate neuronal excitability and maintain a balance between excitation and inhibition in the nervous system. There are two main forms of glutamate decarboxylase, known as GAD65 and GAD67, which differ in their structure and function. These enzymes are primarily found in GABAergic neurons, which are responsible for producing GABA. Proper functioning of glutamate decarboxylase is essential for normal brain activity and can impact conditions such as anxiety and epilepsy.