Nonfunctional epidermal growth factor receptor in cells transformed by Kirsten sarcoma virus

Abstract

The cell membrane receptor for epidermal growth factor (EGF) appears to be a glycoprotein of M r 170,000 and mediates the mitogenic and metabolic responses of cells with EGF receptors (EGF-R). Normal rat kidney (NRK) have about 3 × 10 5 EGF-R per cell. Upon transformation of NRK cells by Kirsten sarcoma virus, the transformed derivative (KNRK) loses the ability to bind 125I-EGF. Membranes from NRK and KNRK cells were included in EGF-dependent phosphorylation reactions to search for evidence of the EGF-R. A phosphorylated protein of M r 170,000 was detected in both NRK and KNRK membranes. The M r 170,000 protein was identified to be EGF-R by immunoprecipitation with monoclonal antibody to the receptor. Furthermore, two-dimensional peptide mapping using trypsin and chymotrypsin digestions of the iodinated receptors from both NRK and KNRK cells showed essentially identical patterns. These data indicate that the EGF-R is present in KNRK cells with apparently the same protein structure as the NRK counterpart.