During neurotransmission, glutamate is released from vesicles of the presynaptic cell, and glutamate receptors (e.g., NMDA Receptor, AMPA Receptor) bind glutamate for activation at the opposing postsynaptic cell. Excitatory amino acid transporters (EAATs) regulate and maintain extracellular glutamate concentrations below excitotoxic levels. In addition, glutamate transporters may limit the duration of synaptic excitation by an electrogenic process in which the transmitter is cotransported with three sodium ions and one proton, followed by countertransport of a potassium ion. Five EAATs (EAAT1-5) have been identified. EAAT1 and EAAT2 are expressed mainly in glia, while EAAT3, EAAT4, and EAAT5 are considered to be neuronal transporters. EAAT3 is found in the perisynaptic areas and cell bodies of glutamatergic and GABAergic neurons. Research studies have implicated abnormal EAAT3 expression in the pathophysiology of Schizophrenia.
