title: Biochemical and genetic analysis of the Drk SH2/SH3 adaptor protein of Drosophila.
abstract: The Drk SH3-SH2-SH3 adaptor protein has been genetically identified in a screen for rate-limiting components acting downstream of the Sevenless (Sev) receptor tyrosine kinase in the developing eye of Drosophila. It provides a link between the activated Sev receptor and Sos, a guanine nucleotide release factor that activates Ras1. We have used a combined biochemical and genetic approach to study the interactions between Sev, Drk and Sos. We show that Tyr2546 in the cytoplasmic tail of Sev is required for Drk binding, probably because it provides a recognition site for the Drk SH2 domain. Interestingly, a mutation at this site does not completely block Sev function in vivo. This may suggest that Sev can signal in a Drk-independent, parallel pathway or that Drk can also bind to an intermediate docking protein. Analysis of the Drk-Sos interaction has identified a high affinity binding site for Drk SH3 domains in the Sos tail. We show that the N-terminal Drk SH3 domain is primarily responsible for binding to the tail of Sos in vitro, and for signalling to Ras in vivo.
authors.affiliation: Zoologisches Institut, Universität Zürich, Switzerland.
authors.forename: T
authors.initials: T
authors.lastname: Raabe
authors.forename: J P
authors.initials: JP
authors.lastname: Olivier
authors.forename: B
authors.initials: B
authors.lastname: Dickson
authors.forename: X
authors.initials: X
authors.lastname: Liu
authors.forename: G D
authors.initials: GD
authors.lastname: Gish
authors.forename: T
authors.initials: T
authors.lastname: Pawson
authors.forename: E
authors.initials: E
authors.lastname: Hafen
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D018076:DNA, Complementary / Q000235:genetics; D004330:Drosophila / Q000235:genetics* / Q000378:metabolism*; D029721:Drosophila Proteins; D005136:Eye Proteins / Q000235:genetics / Q000378:metabolism; D017344:Genes, Insect; D066298:In Vitro Techniques; D007301:Insect Hormones / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D010641:Phenotype; D017354:Point Mutation; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D020664:Son of Sevenless Proteins
chemical_list: D018076:DNA, Complementary; D029721:Drosophila Proteins; D005136:Eye Proteins; D007301:Insect Hormones; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D020664:Son of Sevenless Proteins; C080530:drk protein, Drosophila; D020794:Receptor Protein-Tyrosine Kinases; C056737:sev protein, Drosophila