Epidermal growth factor and potent phorbol tumor promoters induce epidermal growth factor receptor phosphorylation in a similar but distinctively different manner in human epidermoid carcinoma A431 cells.

摘要: When human epidermoid carcinoma A431 cells labeled with 32Pi to steady state specific activity were treated either epidermal growth factor (EGF) or active phorbol ester tumor promoters such as 12-O-tetradecanoylphorbol 13-acetate (TPA) 12,13-dibutyrate, labeling of 160 kDa EGF receptors isolated by immunoprecipitation monoclonal anti-EGF receptor IgG was increased 2- 3-fold. These treatments produced no significant increase in acid-precipitable material present detergent extracts the cells. Phosphoamino acid analysis radiolabeled from these revealed several differences: relative abundance phosphotyrosine EGF, but decreased TPA; overall phosphothreonine remained constant within limits experimental detection TPA. Two-dimensional mapping phosphopeptides and trypsin 9 independent regions, 2 which contained only EGF- TPA-treated two phosphopeptide regions more highly TPA than EGF.