PURIFICATION OF THE EPIDERMAL GROWTH-FACTOR RECEPTOR BY TYROSINE-SEPHAROSE AFFINITY-CHROMATOGRAPHY

The EGF receptor has been purified from human epidermoid carcinoma A431 cells by affinity chromatography on wheat germ agglutinin-agarose and tyrosine-Sepharose. The purified EGF receptor was shown to be homogenous by SDS-polyacrylamide gel electrophoresis and possessed EGF-sensitive tyrosine kinase activity. Kinetic analysis of the autophosphorylation indicated that approximately 1.4 mol of phosphate was incorporated per mol of the EGF receptor. When a synthetic tyrosine-containing peptide was used as a phosphorylatable substrate, the specific activity of the EGF-stimulated kinase was 66 nmol/min/mg.