title: The SH2-containing tyrosine phosphatase corkscrew is required during signaling by sevenless, Ras1 and Raf.
abstract: The sevenless gene encodes a receptor tyrosine kinase which is required for the development of the R7 photoreceptor cell in each ommatidium of the Drosophila eye. We have previously used a sensitized genetic screen to identify mutations, designated Enhancers of sevenless (E(sev)), which affect genes that encode components of the sevenless signaling pathway. Here, we report that one of these mutations, E(sev)1Ae0P is a dominantly inhibiting allele of corkscrew, which encodes an SH2 domain-containing protein tyrosine phosphatase (Perkins et al., 1992). We show that corkscrew function is essential for sevenless signaling and that expression of a membrane-targeted form of corkscrew can drive R7 photoreceptor development in the absence of sevenless function. Furthermore, we have used the dominantly inhibiting corkscrew allele to examine the role of corkscrew during signaling by activated forms of Ras1 and Raf. Our analysis indicates that corkscrew function is still required during signaling by activated forms Ras1 and Raf proteins. These results define a function for corkscrew that is either downstream of Ras1 activation or in a parallel pathway that acts with activated Ras1/Raf to specify R7 photoreceptor development.
authors.affiliation: Department of Biological Sciences, Stanford University, CA 94305, USA.
authors.forename: J D
authors.initials: JD
authors.lastname: Allard
authors.forename: H C
authors.initials: HC
authors.lastname: Chang
authors.forename: R
authors.initials: R
authors.lastname: Herbst
authors.forename: H
authors.initials: H
authors.lastname: McNeill
authors.forename: M A
authors.initials: MA
authors.lastname: Simon
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D004252:DNA Mutational Analysis; D004330:Drosophila / Q000196:embryology; D029721:Drosophila Proteins; D004843:Epistasis, Genetic; D005136:Eye Proteins / Q000235:genetics / Q000502:physiology*; D008562:Membrane Glycoproteins / Q000235:genetics / Q000502:physiology*; D008969:Molecular Sequence Data; D009154:Mutation; D017956:Photoreceptor Cells, Invertebrate / Q000254:growth & development; D017354:Point Mutation; D017346:Protein Serine-Threonine Kinases / Q000502:physiology*; D017027:Protein Tyrosine Phosphatases / Q000235:genetics / Q000502:physiology*; D011518:Proto-Oncogene Proteins / Q000502:physiology*; D019908:Proto-Oncogene Proteins c-raf; D020794:Receptor Protein-Tyrosine Kinases; D015398:Signal Transduction / Q000502:physiology*; D018631:ras Proteins / Q000502:physiology*; D018909:src Homology Domains
chemical_list: D029721:Drosophila Proteins; D005136:Eye Proteins; D008562:Membrane Glycoproteins; D011518:Proto-Oncogene Proteins; D020794:Receptor Protein-Tyrosine Kinases; C056737:sev protein, Drosophila; D017346:Protein Serine-Threonine Kinases; D019908:Proto-Oncogene Proteins c-raf; D017027:Protein Tyrosine Phosphatases; D018631:ras Proteins