FIG. 6.

The 1-6 chimera does not block internalization or recycling of surface Tac into the tubular compartment. HeLa cells expressing Tac and either the 1-6 chimera or 1-6(T31N) were incubated with anti-Tac antibodies (7G7) at 4°C to bind to surface Tac. Excess antibodies were washed off, and the cells were then incubated at 37°C for 30 min in the presence of CD to allow internalization of the Tac antibodies into the endosomal compartment. Cells were then rinsed to remove remaining surface anti-Tac antibodies and either fixed immediately and assessed for Tac antibody internalized by immunofluorescence (Uptake) or warmed to 37°C for 30 min in the absence of CD before fixation. Tac antibody that reappeared on the cell surface was detected by incubation with fluorescently labeled secondary antibodies in the absence of detergent permeabilization (Surface Reappearance). The 1-6 chimera or 1-6(T31N) was subsequently localized in these cells after permeabilization. Bar, 15 μm.