Figure 5.

Inhibition of epidermal growth factor receptor internalization by blocking EGFR dimerization. The EGFR dimerization loop (amino acids 244–259) was deleted and the deletion mutant was tagged with enhanced yellow fluorescent protein (EYFP; ΔCR1–YFP). ΔCR1–YFP or EGFR–YFP was expressed in Cos7 cells by transient transfection and the cells were treated with EGF (100 ng/ml) or Texas red (TR)-conjugated EGF (TR–EGF; 100 ng/ml). (A) The cells were lysed and the protein samples were immunoblotted with indicated antibodies. (B) The cells were crosslinked with bis-(sulphosuccinimidyl suberate) (BS³) and lysed. The protein samples were immunoblotted with an anti-green fluorescent protein (GFP) antibody. (C) The localization of ΔCR1–YFP (green), EGFR–YFP (green) and TR–EGF (red) was shown by intrinsic fluorescence. Scale bar, 20 μm.