title: Aspects of the metabolism of the epidermal growth factor receptor in A431 human epidermoid carcinoma cells.
abstract: The biosynthesis and posttranslational metabolism of the epidermal growth factor (EGF) receptor were examined in the A431 human epidermoid carcinoma cell line. Polyclonal antibody against the receptor specifically immunoprecipitated two [35S]methionine-labeled proteins of Mr = 160,000 and 170,000. Pulse chase experiments showed the Mr = 160,000 protein to be a precursor of the Mr = 170,000 protein. Preincubation with tunicamycin resulted in immunoprecipitation of a single band of Mr = 130,000, whereas monensin inhibited maturation to the Mr = 170,000 form. Digestion of the Mr = 160,000 and 170,000 proteins with endoglycosidase H resulted in the appearance of Mr = 130,000 and 165,000 proteins, respectively. Prolonged pulse-chase experiments indicated that the half-life of the receptor is ca. 20 h in the absence of EGF and 5 h in the presence of EGF. Approximately three- to five-fold more phosphate is incorporated into the mature receptor upon addition of EGF, due primarily to increases in levels of phosphotyrosine and phosphoserine. Phosphate was also present on the Mr = 160,000 protein and the Mr = 130,000 protein found in the presence of tunicamycin.
mesh_terms: D000911:Antibodies, Monoclonal; D002294:Carcinoma, Squamous Cell / Q000378:metabolism*; D002460:Cell Line; D002478:Cells, Cultured; D066246:ErbB Receptors; D006023:Glycoproteins / Q000096:biosynthesis; D006801:Humans; D008970:Molecular Weight; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D011956:Receptors, Cell Surface / Q000276:immunology / Q000378:metabolism*
chemical_list: D000911:Antibodies, Monoclonal; D006023:Glycoproteins; D011956:Receptors, Cell Surface; D066246:ErbB Receptors