CLONING AND CHARACTERIZATION OF A GLUTAMATE TRANSPORTER CDNA FROM HUMAN BRAIN AND PANCREAS

L-Glutamate is the major excitatory neurotransmitter in the brain. Suf ficient removal from the synaptic cleft after neurotransmission by the L-glutamate transport system is essential to prevent excitotoxicity a nd neurotoxicity. We isolated mRNA from human brain and pancreatic isl et cells and screened for sequences of high homology to a previously c haracterized rat brain glutamate transporter. An isolated sequence (GL TR) shows a 87.5% and a 92.5% sequence similarity at the nucleotide an d amino acid level, respectively, with a rat brain specific L-glutamat e transporter but only a 65% homology to the recently cloned human glu tamate/aspartate transporter. The human mRNA is differentially express ed in brain and to a lesser degree in pancreas and in fetal liver. The gene encoding for the newly identified cDNA is located on chromosome 5.