Figure 2.

Antibody internalization assay (with preincubation at 37°C for 10 min). Same as in Figure 1, but the cells transfected with the WT (A) or mutant (B) Vpu expression plasmid were cultured in complete medium with anti-Myc mouse monoclonal antibodies at 37°C instead of 4°C for 10 min, and then fixed with 4% paraformaldehyde either immediately (0 min) or after an additional incubation (20, 50 or 80 min). Squares outline magnified regions where the colocalization of BST-2, Vpu, and a lysosome marker cathepsin D is indicated by arrows. Bars, 10 µm.