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 0.25μM for the binding of EGF to sEGFR. The calculated dissociation constant for EGF-induced sEGFR dimerization was found to be 2.4±0.9μM. These experiments demonstrated that EGF induces receptor dimerization and that two EGF molecules are bound to an EGF-receptor dimer.
