Fig. 4.

UIM proteins and EGFR/Ubmut. (A) φ-NX cells were transfected as indicated above the gels. Lysates (5 mg) were immunoprecipitated (IP) and immunoblotted (IB) as indicated. (B) Immunoelectron microscopy of NR6 expressing EGFR/Ubmut. (Bar, 83 nm.) Arrowheads point to caveolar membranes. Note that in cells expressing the EGFR/FLAG control chimera, eps15 and epsin were never detected in caveolae (data not shown). (C) CHO cells were cotransfected with EGFR/Ubmut and either GFP or GFP-UIM (amino acids 842–897 of eps15) and incubated with rhodamine-EGF (red, Left) or rhodamine-transferrin (red, Center). Merged images are shown. (Right) A quantitative assessment of EGF internalization (3 ng/ml ¹²⁵I-EGF for 15 min at 37°C).