Cloning, expression analysis, and chromosomal mapping of GTPBP2, a novel member of the G protein family.

We have identified a novel gene encoding a protein bearing GTP-binding motifs, the characteristics of GTP-binding proteins (G proteins). The deduced amino acid sequence exhibited the highest overall homology with GTPBP1 and its mouse orthologue GP-1. Hence, we named the gene GTPBP2. The mouse orthologue of this gene, Gtpbp2, showed 98% identity with GTPBP2 over the entire protein (the HGMW-approved nomenclature symbol is GTPBP2 and mouse orthologue is Gtpbp2). A phylogenetic analysis showed GTPBP2 and homologous G proteins (GTPBP1, AGP-1, and CGP-1) did not belong to major G protein families. They formed a distinct branch in the phylogenetic tree, suggesting that they constitute a novel G protein family. A 2. 9kb mRNA was predominantly detected in the testis along with various other organs. In situ hybridization analysis revealed that Gtpbp2 was predominantly expressed in spermatocytes and round-spermatids in the testis. These novel genes were localized to human chromosome 6p21.1-2 and mouse chromosome 17qC-D.