Cloning, genomic organization and chromosomal assignment of the mouse p190-B gene

The p190 family of GTPases consists of at least two different isoforms both containing an N-terminal GTPase and a C-terminal Rho GAP domain. Here we h ave isolated and characterized genomic and cDNA clones spanning the entire coding region of the mouse p190-B gene. Genomic data were obtained by seque ncing plasmid subclones of two overlapping mouse genomic phage clones. Inte restingly, a single 3.9 kb exon was found to contain approx. 80% of the cod ing region of the mouse p190-B protein (amino acid residues 1-1238) includi ng the 5'-untranslated region, the N-terminal GTPase domain and a middle do main of unknown function. Missing from this exon, however, was the C-termin al Rho GAP domain, which was cloned from mouse brain mRNA using reverse tra nscriptase polymerase chain reaction. Comparison of the mouse with the huma n p190-B proteins revealed that approx. 97% of the amino acid residues were identical. Northern analysis of total RNA from a variety of mouse tissues detected ubiquitous expression of two p190-B transcripts of 4.0 and 6.8 kb in size. Analysis of two multilocus genetic crosses localized the mouse gen e, Gfi2, to a position on chromosome 12, consistent with the mapping of the human gene to a position of conserved synteny on chromosome 14. The high l evel of sequence homology between the human and the mouse suggests that the re is a strong selective pressure to maintain the p190-B protein structure. (C) 1998 Elsevier Science B.V. All rights reserved.