FIGURE 4:

Masking/unmasking of a Golgi-to-ER retrieval signal. (A) HeLa cells were transfected with CD4-GFP-SBP-KKTN (top) or CD4-GFP-SBP-KRKAE (bottom) with or without SA (plasmid ratio, 3:2) and biotin. After overnight incubation, cells were incubated for an additional 3 h in the presence of cycloheximide, fixed (but not permeabilized), and stained with anti-CD4 antibody. (B) Cells were transfected with VSVGts045-GFP-SBP-KRKAE with or without streptavidin (plasmid ratio, 3:2). After overnight incubation at 40°C, the cells were switched to the permissive temperature of 32°C for 3 h in the presence of cycloheximide with or without biotin.