Figure 5.

Overexpression of EGFP-OCRL¹⁻¹¹⁹ impairs endocytosis of transferrin. (A) Hela cells were transfected with expression vectors for the indicated GFP-fusion proteins. At 48 h after transfection, cells were incubated with transferrin-Alexa594 for 10 min. After washing and acid stripping, cells were fixed and inspected by fluorescence microscopy. Arrows indicate transfected cells demonstrating reduced transferrin uptake after EGFP-OCRL¹⁻¹¹⁹ transfection and unchanged transferrin uptake after EGFP-OCRL¹⁻¹¹⁹ I74N transfection. Scale bar is 10 μm. (B) Quantification of transferrin uptake. Hela cells were transfected with expression vectors for EGFP-OCRL¹⁻¹¹⁹ (filled squares) or EGFP-OCRL¹⁻¹¹⁹ I74N (filled triangles). After 48 h, uptake of biotinylated transferrin was measured at the indicated time points using an ELISA assay. Values are the mean±s.e. (n=3).