title: Recruitment of Dok-R to the EGF receptor through its PTB domain is required for attenuation of Erk MAP kinase activation.
abstract: Dok (for downstream of tyrosine kinases) proteins are a newly identified family of docking molecules that are characterized by the presence of an amino-terminal pleckstrin homology (PH) domain, a central putative phosphotyrosine-binding (PTB) domain and numerous potential sites of tyrosine phosphorylation [1] [2] [3] [4] [5] [6]. Here, we explore the potential role of the Dok family member Dok-R (also known as p56(Dok2) or FRIP) in signaling pathways mediated by the epidermal growth factor (EGF) receptor. An intact PTB domain in Dok-R was critical for its association with two PTB-binding consensus sites on the EGF receptor and the PH domain further contributed to stable in vivo binding and tyrosine phosphorylation of Dok-R. Multiple sites on Dok-R were tyrosine-phosphorylated following EGF stimulation; phosphorylated Tyr276 and Tyr304 are proposed to dock the tandem Src homology 2 (SH2) domains of the p21(Ras) GTPase-activating protein rasGAP and Tyr351 mediates an association with the SH2 domain of the adapter protein Nck. Interestingly, we have found that Dok-R could attenuate EGF-stimulated mitogen-activated protein (MAP) kinase activation independently of its association with rasGAP. Together, these results suggest that Dok-R has an important role downstream of growth factor receptors as a potential negative regulator of signal transduction.
authors.affiliation: Division of Cancer Biology Research Sunnybrook and Women's College Health Sciences Centre Department of Medical Biophysics University of Toronto Toronto, Ontario, Canada.
authors.forename: N
authors.initials: N
authors.lastname: Jones
authors.forename: D J
authors.initials: DJ
authors.lastname: Dumont
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism*; D002522:Chlorocebus aethiops; D004789:Enzyme Activation; D066246:ErbB Receptors / Q000378:metabolism*; D051380:GRB2 Adaptor Protein; D020935:MAP Kinase Signaling System / Q000502:physiology*; D008969:Molecular Sequence Data; D015513:Oncogene Proteins / Q000378:metabolism; D010750:Phosphoproteins / Q000737:chemistry / Q000378:metabolism*; D010766:Phosphorylation; D011485:Protein Binding; D011499:Protein Processing, Post-Translational; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D055765:Shc Signaling Adaptor Proteins; D014162:Transfection; D018909:src Homology Domains
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D002352:Carrier Proteins; C115089:DOK2 protein, human; D051380:GRB2 Adaptor Protein; C078332:Nck protein; D015513:Oncogene Proteins; D010750:Phosphoproteins; D011506:Proteins; D011993:Recombinant Fusion Proteins; D055765:Shc Signaling Adaptor Proteins; D066246:ErbB Receptors