抄録
The mode of interaction between human epidermal growth factor (hEGF) and its receptor has been investigated by immunochemical studies and a synthetic peptide approach. Two types of monoclonal and five different monospecific polyclonal antibodies against hEGF have been prepared, whose epitopes are regions 1-13, 13-32, 33-53, 33-43, 22-32, and discontinuous sequences of hEGF. Antibody against 22-32 (Type I) and antibody against 33-53 (PRE 4) inhibited the binding of 125I-hEGF to membrane receptor on A 431 cells more markedly than the other antibodies. When hEGF was bound to the receptor, only antibody against 13-32 (PRE 2) could bind to hEGF-receptor complex whereas antibody against 22-32 (Type I) could not. These data suggest that region 13-20 is exposed outside during receptor-binding and both region 22-32 and region 33-53 contact the hEGF receptor. The activity of synthetic peptides corresponding to the amino acid residues 1-13, 13-32, 33-53, 13-20, 22-32, and 33-43 of hEGF was also examined. Out of the six peptides, only 13-32 stimulated DNA synthesis of BALB 3T3 cells. The activity was approximately 1/106 of that of intact hEGF. All of these data suggest that region 22-32 is responsible for binding to the receptor for signal transduction and region 33-53 binds to the receptor to stabilize the ligand-receptor interaction. This dual binding model fits in well with the threedimensional hEGF structure deduced from NMR spectra [Montelione, G.T. et al.(1987) Proc. Natl. Acad. Sci. U.S. 84, 5226-5230].
