Control of expression and maturation of epidermal growth factor receptor

Epidermal growth factor (EGF)-receptor is a 170 kDa transmembrane glycoprotein that contains a ligand-binding external domain, and a catalytically active cytoplasmic region. The expression of this receptor as well as a 100 kDa homolog that contains only the external domain is enhanced by the ligand EGF. EGF acts at transcriptional and post-transcriptional levels. To dissociate these pre-translational effects and the effects of EGF on receptor polypeptide synthesis from these on receptor export, pulse-chase experiments were conducted. These studies indicate that EGF stimulates post-translational transport and processing of the receptor, and this stimulation can occur in the absence of new protein synthesis. Other studies show that EGF accelerates at least two slow events in receptor maturation--the deoxynojirimycin sensitive processing in endoplasmic reticulum (ER) and the swainsonine sensitive processing in Golgi. The results suggest that EGF may influence one or more of the rate determining steps that control receptor export from ER, and this may represent yet another aspect of EGF action that contributes to the positive regulation of EGF-receptor protein expression.