Abstract
We have identified a Drosophila gene that has substantial sequence homology to a distinct class of proto-oncogenes that includes DBL, VAV, Tiam-1, ost and ect-2. It has predicted Rho or Rac guanine exchange factor (Rho/RacGEF) and pleckstin homology (PH) domains with the PH immediately downstream of the Rho/RacGEF. Rho/RacGEFs catalyze the dissociation of GDP from the Rho/Rac subfamily of Ras-like GTPases, thus activating the target Rho/Rac (Takai et al. (1995) Trends Biochem. Sci. 20, 227-231]. Members of the Rho/Rac subfamily regulate organization of the actin cytoskeleton, which controls the morphology, adhesion and motility of cells (Nobes et al. (1995) J. Cell Sci. 108, 225 233; Ridley and Hall (1992) Cell 70, 389-399; Ridley et al. (1992) Cell 70, 401-410]. Message from this gene is found throughout oogenesis and embryogenesis. Of particular interest, message is most abundant in furrows and folds of the embryo where cell shapes are changing and the cytoskeleton is likely to be undergoing reorganization.
