Functional state of the epidermal growth factor-receptor complexes during their internalization in A-431 cells.

Functional state of internalized epidermal growth factor (EGF) receptor in A-431 cells has been studied. The use of photoaffinity [125I]EGF derivative allowed us to establish that inside the cell the EGF retains its connection with the receptor. With the help of polyclonal antibodies to phosphotyrosine, it has been shown that EGF-receptor complexes maintain their phosphorylated state during internalization. The internalized EGF receptor kinase as well as that localized in the plasma membrane appeared to be able to phosphorylate synthetic peptide substrate introduced into the cell.