Epidermal growth factor receptor structure, regulation, mitogenic signalling and effects of activation.

The biological effects of epidermal growth factor (EGF) and transforming growth factor-alpha (TGF-alpha) are mediated by an interaction with a specific cell surface receptor having both intra- and extracellular domains. The structure of the intracellular domain can be closely aligned with retroviral protein tyrosine kinases. Upon ligand-binding there is a change in conformation of the extracellular domain, the receptor being converted to dimeric. Dimeric receptor has a higher rate of catalysis than monomeric and rapidly becomes phosphorylated. This form of the receptor now associates with and phosphorylates enzymes such as phospholipase-C, altering their catalytic activity and subcellular distribution This system appears to stimulate the effects of epidermal growth factor receptor(EGFr) activation, notably proliferation, morphology, paracrine effects and differentation.