DRG represents a family of two closely related GTP-binding proteins

In a previous publication we identified a novel human GTP-binding protein t hat was related to DRG, a developmentally regulated GTP-binding protein fro m the central nervous system of mouse. Here we demonstrate that both the hu man and the mouse genome possess two closely related drg genes, termed drg1 and drg2. The two genes share 62% sequence identity at the nucleotide and 58% identity at the protein level. The corresponding proteins appear to con stitute a separate family within the superfamily of the GTP-binding protein s. The DRG1 and the DRG2 mRNA are widely expressed in human and mouse tissu es and show a very similar distribution pattern. The human drg1 gene is loc ated on chromosome 22q12, the human drg2 gene on chromosome 17p12. Distantl y related species including Caenorhabditis elegans, Schizosaccharomyces pom be and Saccharomyces cerevisiae also possess two drg genes. In contrast, th e genomes of archaebacteria (Halobium, Methanococcus, Thermoplasma) harbor only one drg gene, while eubacteria do not seem to contain any. The high co nservation of the polypeptide sequences between distantly related organisms indicates an important role for DRG1 and DRG2 in a fundamental pathway. (C ) 2000 Elsevier Science B.V. All rights reserved.