Figure 5.

Replacement of YQRL in the cytosolic domain of TGN38 with the lysosomal targeting signal, YQTI, does not affect delivery of TGN38 from the cell surface to the TGN. Stably transfected Hela cells expressing TGN38 wild-type protein (A and B) or TGN38 with the lysosomal targeting signal, YQTI, replacing YQRL (C–F) were incubated in the presence of an mAb to TGN38, 2F7.1, and internalization was allowed to occur at 37°C for 2 h. The localization of the wild-type and mutant proteins is shown to coincide with the endogenous TGN46 marker (B and C). There is no overlap in distribution of the mutated protein with the endogenous lysosomal marker cathepsin D (F).