Ligand-induced activation of epidermal growth factor receptor in intact rat mammary adenocarcinoma cells without detectable receptor phosphorylation.

摘要: Expression and function of epidermal growth factor receptor (EGFR) was investigated in a metastatic cell clone (MTLn3) derived from the 13762NF rat mammary adenocarcinoma. No phosphorylation could be identified intact cells or membrane preparations, while EGF-dependent substrates occurred cells. Indications for active suppression came fact that EGFRs bound immunocomplexes associated with cytoskeleton detergent treated were able to undergo basal EGF-induced vitro. Cross-linking experiments 125I-EGF, as well [35S]methionine labeling followed by immunoprecipitation specific antibodies readily detected MTLn3 expected 170-kDa EGFR protein. In addition, two proteins molecular masses 420-480 95 kDa specifically 125I-EGF on sparse cultures A431 Phosphorylation molecule isolated cells, but 95-kDa never phosphorylated. While presence alternative forms highly unexpected, our observations inefficient autophosphorylation are agreement other recent reports suggest EGFR-mediated signal transduction can an event independent autophosphorylation.