Analysis of protein-protein interactions involved in the activation of the Shc/Grb-2 pathway by the ErbB-2 kinase.
In murine fibroblasts activation of the Shc/Grb-2 pathway by the ErbB-2 kinase involves tyrosine phosphorylation of Shc products and the formation of Shc/ErbB-2, Shc/Grb-2 and Grb-2/ErbB-2 complexes. Tyr 1139 of ErbB-2 bound to the Grb-2 SH2 domain in vitro as well as in intact cells. Tyr 1221 and 1248 are binding sites of gp185ErbB-2 for Shc SH2 domain in vitro whereas Tyr 1196 and 1248 are major binding sites of ErbB-2 for Shc PTB domain. Inhibition of Shc/ErbB-2 complex formation in intact cells was obtained by simultaneous mutational inactivation of Shc SH2 and Shc PTB binding sites of gp185ErbB-2. Shc/ErbB-2 complexes are formed upon activation of the ErbB-2 kinase and tyrosine phosphorylation of Shc proteins; they are located in both cytosol and cellular membranes. ErbB-2 activation induces also translocation of Grb-2 from cytosol to membranes. This network of protein-protein interactions may reflect the ability of the Shc/Grb-2 pathway to act as a molecular switch controlling different cellular functions regulated by RTK activation. In fact the Ras GDP exchanger mSOS was recruited in Grb-2/ErbB-2 complexes; furthermore besides mSOS, other polypeptides present in either cytosolic or membrane preparations were able to complex in vitro with Grb-2 SH3 domains.
D016475:3T3 Cells; D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D000595:Amino Acid Sequence; D000818:Animals; D001667:Binding, Competitive; D051380:GRB2 Adaptor Protein; D046911:Macromolecular Substances; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D010748:Phosphopeptides / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D011485:Protein Binding; D011506:Proteins / Q000378:metabolism* / Q000502:physiology*; D020794:Receptor Protein-Tyrosine Kinases / Q000502:physiology*; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000502:physiology*; D055765:Shc Signaling Adaptor Proteins; D015398:Signal Transduction; D020664:Son of Sevenless Proteins; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D018909:src Homology Domains
D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D051380:GRB2 Adaptor Protein; D046911:Macromolecular Substances; D008565:Membrane Proteins; D010748:Phosphopeptides; D010750:Phosphoproteins; D011506:Proteins; D020794:Receptor Protein-Tyrosine Kinases; D018719:Erb-b2 Receptor Tyrosine Kinases; D055765:Shc Signaling Adaptor Proteins; D020664:Son of Sevenless Proteins; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; C495949:Grb2 protein, mouse; C528034:Shc1 protein, mouse