title: The v-Src SH3 domain binds phosphatidylinositol 3'-kinase.
abstract: Fibroblasts transformed by v-src or by related oncogenes encoding activated tyrosine kinases contain elevated levels of polyphosphoinositides with phosphate at the D-3 position of the inositol ring, as a result of the activation of phosphatidylinositol (PI) 3'-kinase. v-src-transformed cells also contain increased levels of PI 3'-kinase activity immunoprecipitable with anti-phosphotyrosine antibodies; furthermore, PI 3'-kinase can be detected in association with the v-Src tyrosine kinase. To identify regions of v-Src that can interact with PI 3'-kinase, the v-Src SH2 and SH3 domains were expressed in bacteria and incubated with lysates of normal chicken embryo fibroblasts. In vitro, the v-Src SH3 domain, but not the SH2 domain, bound PI 3'-kinase in lysates of uninfected chicken embryo fibroblasts. Substitutions of two highly conserved SH3 residues implicated in ligand binding abolished the ability of the v-Src SH3 domain to associate with PI 3'-kinase. Furthermore, the v-Src SH3 domain bound in vitro to the amino-terminal region of the p85 alpha subunit of PI 3'-kinase. These results suggest that the v-Src SH3 domain may mediate an interaction between the v-Src tyrosine kinase and PI 3'-kinase, by direct binding to p85.
authors.affiliation: Division of Molecular and Developmental Biology, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada.
authors.forename: X
authors.initials: X
authors.lastname: Liu
authors.forename: L E
authors.initials: LE
authors.lastname: Marengere
authors.forename: C A
authors.initials: CA
authors.lastname: Koch
authors.forename: T
authors.initials: T
authors.lastname: Pawson
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002451:Cell Compartmentation; D002462:Cell Membrane / Q000201:enzymology; D002478:Cells, Cultured; D002642:Chick Embryo; D066298:In Vitro Techniques; D008969:Molecular Sequence Data; D015688:Oncogene Protein pp60(v-src) / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D010770:Phosphotransferases / Q000378:metabolism*; D019000:Phosphotyrosine; D011485:Protein Binding; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism
chemical_list: D010750:Phosphoproteins; D019000:Phosphotyrosine; D014443:Tyrosine; D010770:Phosphotransferases; D019869:Phosphatidylinositol 3-Kinases; D015688:Oncogene Protein pp60(v-src)