title: Ligand-binding enhances the affinity of dimerization of the extracellular domain of the epidermal growth factor receptor.
abstract: We studied the dimerization of the recombinant soluble extracellular domain of the epidermal growth factor receptor (sEGFR) in response to EGF-binding using multi-angle laser light scattering with size exclusion chromatography (SEC-MALLS). In the absence of EGF, sEGFR behaved as a monomer. However, upon EGF-binding, sEGFR formed a dimer with the stoichiometry of two EGF molecules bound to two sEGFR molecules [(EGF)2-(sEGFR)2]. We analyzed the chemical equilibrium of the dimer formation by SEC-MALLS using a dissociation constant of 0.25 microM for the binding of EGF to sEGFR. The calculated dissociation constant for EGF-induced sEGFR dimerization was found to be 2.4 +/- 0.9 microM. These experiments demonstrated that EGF induces receptor dimerization and that two EGF molecules are bound to an EGF-receptor dimer.
authors.affiliation: Department of Molecular Physiology, The Tokyo Metropolitan Institute of Medical Science, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Odaka
authors.forename: D
authors.initials: D
authors.lastname: Kohda
authors.forename: I
authors.initials: I
authors.lastname: Lax
authors.forename: J
authors.initials: J
authors.lastname: Schlessinger
authors.forename: F
authors.initials: F
authors.lastname: Inagaki
mesh_terms: D001665:Binding Sites; D002850:Chromatography, Gel / Q000379:methods; D019281:Dimerization; D004815:Epidermal Growth Factor / Q000737:chemistry / Q000378:metabolism*; D066246:ErbB Receptors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D007834:Lasers; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012542:Scattering, Radiation; D012995:Solubility
chemical_list: D011994:Recombinant Proteins; D004815:Epidermal Growth Factor; D066246:ErbB Receptors