title: Rasputin, the Drosophila homologue of the RasGAP SH3 binding protein, functions in ras- and Rho-mediated signaling.
abstract: The small GTPase Ras plays an important role in many cellular signaling processes. Ras activity is negatively regulated by GTPase activating proteins (GAPs). It has been proposed that RasGAP may also function as an effector of Ras activity. We have identified and characterized the Drosophila homologue of the RasGAP-binding protein G3BP encoded by rasputin (rin). rin mutants are viable and display defects in photoreceptor recruitment and ommatidial polarity in the eye. Mutations in rin/G3BP genetically interact with components of the Ras signaling pathway that function at the level of Ras and above, but not with Raf/MAPK pathway components. These interactions suggest that Rin is required as an effector in Ras signaling during eye development, supporting an effector role for RasGAP. The ommatidial polarity phenotypes of rin are similar to those of RhoA and the polarity genes, e.g. fz and dsh. Although rin/G3BP interacts genetically with RhoA, affecting both photoreceptor differentiation and polarity, it does not interact with the gain-of-function genotypes of fz and dsh. These data suggest that Rin is not a general component of polarity generation, but serves a function specific to Ras and RhoA signaling pathways.
authors.affiliation: LMG, NICHD, NIH, MSC 2785, Bethesda, MD 20892, USA.
authors.forename: C
authors.initials: C
authors.lastname: Pazman
authors.forename: C A
authors.initials: CA
authors.lastname: Mayes
authors.forename: M
authors.initials: M
authors.lastname: Fanto
authors.forename: S R
authors.initials: SR
authors.lastname: Haynes
authors.forename: M
authors.initials: M
authors.lastname: Mlodzik
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000502:physiology*; D003600:Cytosol / Q000378:metabolism; D004265:DNA Helicases; D004268:DNA-Binding Proteins / Q000235:genetics; D004330:Drosophila / Q000235:genetics / Q000502:physiology; D029721:Drosophila Proteins; D015870:Gene Expression; D006801:Humans; D008969:Molecular Sequence Data; D016296:Mutagenesis; D017956:Photoreceptor Cells, Invertebrate / Q000196:embryology* / Q000502:physiology; D000075223:Poly-ADP-Ribose Binding Proteins; D020365:RNA Helicases; D000067776:RNA Recognition Motif Proteins; D011987:Receptors, Steroid / Q000235:genetics; D012097:Repressor Proteins / Q000235:genetics / Q000502:physiology*; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D018631:ras Proteins / Q000378:metabolism*; D020742:rhoA GTP-Binding Protein / Q000378:metabolism
chemical_list: D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D000075223:Poly-ADP-Ribose Binding Proteins; D000067776:RNA Recognition Motif Proteins; D011987:Receptors, Steroid; D012097:Repressor Proteins; C492054:rin protein, Drosophila; C094295:svp protein, Drosophila; D004265:DNA Helicases; C116070:G3BP1 protein, human; D020365:RNA Helicases; D018631:ras Proteins; D020742:rhoA GTP-Binding Protein