title: Genomic organization and regulation of the vav proto-oncogene.
abstract: Vav and vav2 are members of the dbl family of guanine nucleotide exchange factors (GEF) for the rho/rac family of GTP binding proteins. Vav is expressed primarily in hematopoietic cells, while vav2 has a wider tissue distribution. The genomic structure of the human vav proto-oncogene was studied by identifying and sequencing all 27 exons of the gene from overlapping P1 and cosmid clones. The gene spans a 77-kb region on chromosome 19. In contrast, the coding region of vav2 is distributed over 30 exons spanning 227-kb. The overall organization of the exons which encode both proteins was found to be similar. In humans, alternative splicing of exons 6, 16 and 28 generated at least two distinct vav2 mRNA species. Several differences from the original vav cDNA sequence were noted. The most important difference was the identification of amino acid 718 as isoleucine, rather than threonine. This change warrants the reclassification of the vav SH2 domain as a type 3 SH2, instead of a type 2 SH2 as originally proposed by Songyang et al. (Mol. Cell. Biol. 14 (1994) 2777-2785). A series of vav promoter deletions were constructed using the enhanced green fluorescent protein (EGFP) as a reporter gene. A 23-bp segment that included a potential CBF/AML-1 binding site was found to be essential for EGFP expression in U937 cells. The same constructs were not active in HeLa cells, which do not express vav. A potential c-myb DNA binding site within the vav promoter was not required for EGFP expression.
authors.affiliation: Department of Pharmacology, University of Nebraska Medical Center, 986260 Nebraska Medical Center, Omaha, NE, USA.
authors.forename: D J
authors.initials: DJ
authors.lastname: Denkinger
authors.forename: C R
authors.initials: CR
authors.lastname: Borges
authors.forename: C L
authors.initials: CL
authors.lastname: Butler
authors.forename: A M
authors.initials: AM
authors.lastname: Cushman
authors.forename: R S
authors.initials: RS
authors.lastname: Kawahara
mesh_terms: D016475:3T3 Cells; D017398:Alternative Splicing; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D018797:Cell Cycle Proteins; D002459:Cell Fusion; D005786:Gene Expression Regulation; D006367:HeLa Cells; D006801:Humans; D007438:Introns; D051379:Mice; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D051567:Proto-Oncogene Proteins c-vav; D013234:Stem Cells / Q000378:metabolism; D014162:Transfection
chemical_list: D018797:Cell Cycle Proteins; C000715470:MAS1 protein, human; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins; D051567:Proto-Oncogene Proteins c-vav; C496618:VAV1 protein, human; C496619:Vav1 protein, mouse