title: Small GTPase Rac1: structure, localization, and expression of the human gene.
abstract: Rac1 is a member of the Rho family of small GTPases involved in signal transduction pathways that control proliferation, adhesion, and migration of cells during embryonic development and invasiveness of tumor cells. Here we present the complete structure of the human RAC1 gene and characterize its expression. The gene comprises 7 exons over a length of 29 kb and is localized to chromosome 7p22. The GC-rich gene promoter shows characteristics of a housekeeping gene and Northern blot studies revealed ubiquitous expression of two rac1 transcripts, 1.2 and 2.5 kb in size. The two transcripts are expressed in tissue-specific ratios, reflecting competition between two alternative polyadenylation sites. The RAC1 but not RAC2 gene contains an additional exon 3b that is included by alternative splicing into the variant Rac1b, a constitutively active mutant which induces the formation of lamellipodia in fibroblasts. These data indicate that the RAC1 gene encodes two signaling GTPases. The gene structure reported here will enable studies on the regulation of RAC1 expression during tumorigenesis and development.
authors.affiliation: Centre for Human Genetics, National Institute of Health 'Dr. Ricardo Jorge,', Lisbon, 1649-016, Portugal.
authors.forename: P
authors.initials: P
authors.lastname: Matos
authors.forename: J
authors.initials: J
authors.lastname: Skaug
authors.forename: B
authors.initials: B
authors.lastname: Marques
authors.forename: S
authors.initials: S
authors.lastname: Beck
authors.forename: F
authors.initials: F
authors.lastname: Veríssimo
authors.forename: C
authors.initials: C
authors.lastname: Gespach
authors.forename: M G
authors.initials: MG
authors.lastname: Boavida
authors.forename: S W
authors.initials: SW
authors.lastname: Scherer
authors.forename: P
authors.initials: P
authors.lastname: Jordan
mesh_terms: D020121:5' Untranslated Regions / Q000235:genetics; D000199:Actins / Q000502:physiology; D017398:Alternative Splicing; D000595:Amino Acid Sequence; D001483:Base Sequence; D002874:Chromosome Mapping; D002897:Chromosomes, Human, Pair 7; D003599:Cytoskeleton / Q000502:physiology; D004247:DNA / Q000032:analysis; D005091:Exons; D005347:Fibroblasts / Q000502:physiology; D005786:Gene Expression Regulation; D015894:Genome, Human; D006801:Humans; D007438:Introns; D007621:Karyotyping; D008969:Molecular Sequence Data; D008970:Molecular Weight; D011401:Promoter Regions, Genetic / Q000235:genetics*; D014162:Transfection; D020830:rac1 GTP-Binding Protein / Q000235:genetics* / Q000302:isolation & purification
chemical_list: D020121:5' Untranslated Regions; D000199:Actins; D004247:DNA; D020830:rac1 GTP-Binding Protein