FIGURE 3.

NPC1, but not NPC2, is required for amine (CQ)-induced co-localization of lysosomes with late endosomes. A, under normal cell culture conditions very few lysosomes co-localize with late endosomes, as was observed from immunofluorescence analysis of cells probed for the cation-independent (CI)-MPR and LAMP1 (late endosome- and lysosome-specific proteins, respectively). When wild type cells are exposed to high concentrations of the lysosomotropic amine (100 μm CQ for 3 h), the degree of lysosome co-localization with late endosomes was significantly enhanced. B, cells with mutations in NPC1 did not show enhanced late endosome/lysosome co-localization when exposed to CQ. C and D, cells with mutations in NPC2 (both GM17910 and GM18455 cell lines) behaved similarly to wild type cells in their response to CQ treatment. Images are representative of cells observed from at least three independent experiments. The percent co-localization is shown in each merge panel.