Fig. 3.

Accumulation of sialylated molecules within endosomes of NPC cells can be attributed largely to impaired recycling. (A) Ac₄ManNAz-labeled NPC1-null and NPC2-deficient fibroblasts were incubated with 0.5 mg/mL Alexa Fluor 647–conjugated dextran for 12 h and then chased for 3 h to allow internalization of this endocytic tracer. Cells were visualized by confocal microscopy. Arrows denote the lack of colocalization between internalized dextran and sialylated molecules within peripheral vesicles. (B) Ac₄ManNAz-labeled NPC1-null and NPC2-deficient fibroblasts were incubated with dextran as above and costained with filipin. Cells were visualized by fluorescence microscopy. n = 20–22 cells scored per condition; three separate experiments.