Glutamate is the main excitatory neurotransmitter in the brain. To date five glutamate Transporters have been cloned: GLAST (EAAT1), GLT1 (EAAT2), EAAC1 (EAAT3), EAAT4, and EAAT5. These transporters are believed to be critical in reducing potentially toxic extracellular concentration of glutamate by rapid uptake into nerve terminals and glial cells. Glutamate transporters (525-573aa) display about 55% homology and are predicted to contain up to 6-10 transmembrane domains. Immunolocalization studies indicate that GLT1 is localized in astroglial cells throughout the brain and spinal cord. EAAC1 is specific for certain neurons and purkinje cells, and specifically enriched in cortex, hippocampus, and caudate-putamen and confined to presynaptic and postsynaptic elements. GLAST has been observed in both neuron and astroglia. It is most abundant in Bergmann glia, cortex, hippocampus and cerebellum. EAAT4 has properties of ligand gated Cl-channel. It is localized mainly in cerebellar Purkinje cells in rat and human CNS. EAAT5 has only been cloned from human. It is primarily expressed in retina. Human EAAT5 glutamate transporter is a 560 amino acid transmembrane protein. It is expressed predominantly in the retina. A 21AA synthetic peptide near the cytoplasmic, C-terminus of human EAAT5 (1) was synthesized, conjugated to KLH, and antibodies generated in rabbits. The antibodies have been affinity purified using the control peptide-Sepharose.