title: Epidermal growth factor receptor targeting prevents uncoupling of the Grb2-SOS complex.
abstract: Insulin stimulates the Ras/Raf/MEK/ERK pathway leading to feedback phosphorylation of the Ras guanylnucleotide exchange protein SOS and dissociation of Grb2 from SOS. Even though epidermal growth factor (EGF) also stimulates ERK activity and phosphorylation of SOS similar to insulin, EGF induces a dissociation of the Grb2-SOS complex from Shc. To determine the molecular basis for this difference, we examined the signaling properties of a mutant EGF receptor lacking the five major autophosphorylation sites. Although EGF stimulation of the mutant EGF receptor activates ERK and phosphorylation of both Shc and SOS, it fails to directly associate with either Shc or Grb2. However, under these conditions EGF induces a dissociation of the Grb2-SOS complex suggesting a role for receptor and/or plasma membrane targeting in the stabilization of Grb2-SOS interaction. Consistent with this hypothesis, expression of an SH2 domain Grb2 mutant which is unable to mediate plasma membrane targeting of the Grb2-SOS complex results in both insulin- and EGF-stimulated uncoupling of Grb2 from SOS. Furthermore, a plasma membrane-bound Grb2 fusion protein remains constitutively associated with SOS. Together, these data demonstrate that EGF stimulation prevents the feedback uncoupling of Grb2 from SOS by inducing a persistent plasma membrane receptor targeting of the Grb2-SOS complex.
authors.affiliation: Department of Physiology & Biophysics, University of Iowa, Iowa City, 52242, USA.
authors.forename: K H
authors.initials: KH
authors.lastname: Holt
authors.forename: S B
authors.initials: SB
authors.lastname: Waters
authors.forename: S
authors.initials: S
authors.lastname: Okada
authors.forename: K
authors.initials: K
authors.lastname: Yamauchi
authors.forename: S J
authors.initials: SJ
authors.lastname: Decker
authors.forename: A R
authors.initials: AR
authors.lastname: Saltiel
authors.forename: D G
authors.initials: DG
authors.lastname: Motto
authors.forename: G A
authors.initials: GA
authors.lastname: Koretzky
authors.forename: J E
authors.initials: JE
authors.lastname: Pessin
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D016466:CHO Cells; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D006224:Cricetinae; D004815:Epidermal Growth Factor / Q000494:pharmacology; D066246:ErbB Receptors / Q000502:physiology*; D051380:GRB2 Adaptor Protein; D006801:Humans; D007328:Insulin / Q000502:physiology; D008565:Membrane Proteins / Q000378:metabolism*; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000378:metabolism; D011485:Protein Binding; D011506:Proteins / Q000378:metabolism*; D011972:Receptor, Insulin / Q000378:metabolism; D011994:Recombinant Proteins; D015398:Signal Transduction; D020664:Son of Sevenless Proteins; D018909:src Homology Domains
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D051380:GRB2 Adaptor Protein; C495948:GRB2 protein, human; D007328:Insulin; D008565:Membrane Proteins; D011506:Proteins; D011994:Recombinant Proteins; D020664:Son of Sevenless Proteins; D019000:Phosphotyrosine; D004815:Epidermal Growth Factor; D066246:ErbB Receptors; D011972:Receptor, Insulin; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases