Figure 4.

Replacement of AGYQTI in the cytosolic domain of lgp120 with the TGN38 steady-state localization signal, SDYQRL, has no effect on the delivery of lgp120 to lysosomes. Hela cells were stably transfected with either a wild-type lgp120 construct (A and B) or a construct containing a mutated lgp120 cytosolic targeting sequence (C–F). Uptake experiments were performed using the mAb to lgp120. Both the wild-type lgp120 protein and the protein containing the TGN38 localization signal were internalized and delivered to a lysosomal/endosomal compartment as demonstrated by colocalization with endogenous human cathepsin D (B and D). The mutated protein showed no colocalization with the endogenous TGN46 (F).