The kinase domain and membrane localization determine intracellular interactions between epidermal growth factor receptors.
Receptor tyrosine kinases play a central role in cellular growth, differentiation, and oncogenesis. All of these responses are triggered by growth factors interacting with the extracellular domain of transmembrane-spanning receptors, leading to dimerization and activation of an intrinsic tyrosine-specific kinase activity by an allosteric mechanism. Precise mechanisms of receptor dimerization remain poorly understood, and current models suggest that the ligand binding domain plays a major determining role. To examine the role of the intracellular domain in the association of juxtaposing receptor molecules, the full-length epidermal growth factor receptor was transiently co-expressed in human 293 fibroblasts with a truncated receptor that lacks the extracellular domain. After metabolic labeling with [35S]methionine, the association of these receptor constructs was monitored by co-immunoprecipitation with an extracellular domain-specific antibody. Specific interactions found between these receptors were independent of ligand binding or an intact ATP-binding site. Truncated receptors that had sequences necessary for membrane localization, and that were capable of interacting with full-length receptor tyrosine kinase, also displayed constitutive kinase activity as well as the capacity to transphosphorylate kinase-negative receptors. Receptor co-immunoprecipitation occurred between constructs that comprise the intracellular domains of the epidermal growth factor and beta-platelet-derived growth factor receptors, and HER-2. Subsequent deletion analysis has identified the major region of epidermal growth factor receptor intracellular interaction to be within the kinase domain.
Chantry
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Department of Biochemistry, Charing Cross and Westminster Medical School, London, United Kingdom.
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002460:Cell Line; D066246:ErbB Receptors / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D006801:Humans; D007668:Kidney; D008024:Ligands; D051379:Mice; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009838:Oligodeoxyribonucleotides; D019000:Phosphotyrosine; D017354:Point Mutation; D021382:Protein Sorting Signals / Q000096:biosynthesis / Q000235:genetics; D017479:Receptors, Platelet-Derived Growth Factor / Q000302:isolation & purification / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D017384:Sequence Deletion; D014443:Tyrosine / Q000031:analogs & derivatives / Q000032:analysis / Q000378:metabolism
D008024:Ligands; D009838:Oligodeoxyribonucleotides; D021382:Protein Sorting Signals; D011994:Recombinant Proteins; D019000:Phosphotyrosine; D014443:Tyrosine; D066246:ErbB Receptors; D017479:Receptors, Platelet-Derived Growth Factor