STRUCTURE AND CHROMOSOMAL ASSIGNMENT TO 22Q12 AND 17QTER OF THE RAS-RELATED RAC2 AND RAC3 HUMAN GENES

Members of the Rho/Rac/Cdc42Hs family of GTPases have been shown to pa rticipate in many aspects of the signaling of cell growth and differen tiation. Although the biochemical properties of these GTPases have bee n extensively studied, very little is known about the structure of the corresponding genes. To gain insight on the evolution of the Rho fami ly, we were interested in studying the genomic structure of several me mbers. We report here the structure and the localization to 22q12 of t he human Rac2 gene, as well as the localization to 17qter of Rac3, a n ew member closely related to Rac1 and Rac2. Unlike the structure of it s closest relative ARH-G gene, which contains a single intron, Rac2 is made of at least 7 exons, spanning over 18 kb of DNA. Comparison of g ene structure and exonic borders suggests that the emergence of the wh ole superfamily took place early during evolution. (C) 1997 Academic P ress.