CLONING AND CHARACTERIZATION OF CDNAS ENCODING PUTATIVE GLUTAMATE TRANSPORTERS FROM CAENORHABDITIS-ELEGANS AND ONCHOCERCA-VOLVULUS

We report the identification and partial characterization of cDNAs enc oding for putative glutamate transporters from the free-living nematod e Caenorhabditis elegans and the filarial parasite Onchocerca volvulus . Glutamate transporters can be used as reliable markers for identifyi ng cells and neurons that synaptically release glutamate and aspartate . An amplified PCR fragment containing a highly conserved amino acid h eptamer found in all vertebrate glutamate transporters was used to scr een a C. elegans cDNA library. Two full-length cDNA sequences from C. elegans were deduced from the isolated cDNA clones and RT-PCR products with the splice leader. The two C. elegans cDNA sequences differ by o nly 97 nucleotides at the 5' end. The C. elegans glutamate transporter gene glt-1 spans at least 2.9 kb of chromosomal DNA and possesses nin e exons and eight introns. Primers directed to the CeGlt cDNA were use d with O. volvulus first-strand cDNA to amplify and isolate the O. vol vulus cDNA homolog. The C. elegans and O. volvulus glutamate transport ers are 98% identical over 492 amino acids to each other and 52 to 58% identical to the mammalian glutamate transporters. Antibodies generat ed against partial coding regions of the C. elegans glutamate transpor ter recognized a protein of approximately 66 kDa in C. elegans and O. volvulus protein extracts.