Molecular cloning, expression characterization, and mapping of a novel putative inhibitor of Rho GTPase activity, RTKN, to D2S145-D2S286

The Rho proteins are a class of small molecular GTPases that regulate multiple fundamental cellular processes by mediating the G-protein-coupled receptor signaling pathway Rhotekin, which is one of the downstream target molecules of Rho with a Rho binding motif class I domain, can inhibit endogenous or RhoGAP-stimulating Rho GTPase activity to regulate the signaling pathway. Here, a novel human cDNA containing an intact open reading frame that encodes 544 amino acids has been identified. As this putative protein shares 84.6% amino acid identity with mouse Rhotekin, and has a tandem Rho binding domain class 1 and Pleckstrin homology domain, it was regarded as a human homologue of the mouse Rhotekin and assigned a symbol of RTKN. With the human Rhotekin cDNA as a probe, Northern hybridization revealed that a 4.0-kb transcript was expressed at a high level in prostate and at a middle level in 13 of 16 tissues examined, but it cannot be detected in liver and lung tissues. Meanwhile, a 2.4-kb transcript was expressed at a middle level in prostate and another 3.0-kb transcript in kidney. In addition, the RTKN gene was localized to chromosome 2p13 between markers D2S145 at 6.94 cR (LOD > 12) and D2S286 at 8.12 cR (LOD > 9.7) by radiation hybrid panel mapping. Compared with BAC clone AC005041 sequence, there were 12 exons for the RTKN gene and it spanned a 16.5-kb genomic region. (C) 2000 Academic Press.