Real-time measurements of kinetics of EGF binding to soluble EGF receptor monomers and dimers support the dimerization model for receptor activation

We have tested one aspect of the allosteric dimerization model for the activation of EGF receptor (EGFR) by EGF:whether EGF binding favors dimerization of the receptor. For this to be true, EGF molecules must bind with higher affinity to dimeric receptors than to monomeric receptors. We have tested this directly in a defined system using the soluble, extracellular ligand binding domain of EGFR monomers (sEGFR) and sEGFR dimers stabilized by treatment with a covalent cross-linking agent. We describe real-time kinetic measurements of EGF binding to receptor monomers and dimers employing the method of total internal reflection (surface plasmon resonance)