Figure 4.

NPC1-containing organelles display reduced movement in cells lacking functional NPC1. To monitor the movements of the NPC1-containing compartment in cells lacking functional NPC1, VAMP7-FP or NPC1(P692S)-FP was transiently transfected into CT60 cells to mark the abnormal organelles. Representative tracks for VAMP7-FP are shown in A. Quantification of the movement of 100 randomly chosen organelles from five cells (B) shows that the speed and displacement of these organelles are severely decreased in CT60 cells. Observations of all the fluorescent organelles within cells showed that the fraction engaged in vectorial transport is decreased in cells lacking functional NPC1 or expressing an NPC1 mutant with reduced function (P692S) (C). Bar, 5 μ m. Video 5 accompanies Figure 4A. Reduced movement of VAMP7-FP organelles in NPC1 mutant cells. Images were acquired every second for 1 min and played back at a rate of six images per second.