Fig. 1. ER export of VSVG-FP and Golgi redistribution upon microtubule depolymerization. (A) Confocal images of living COS7 cells coexpressing GalT-YFP (green) and VSVG-CFP (red). For complete microtubule depolymerization, cells were transferred to ice for 20 minutes following a 24 hour incubation at the nonpermissive temperature (40°C) to accumulate VSVG in the ER. Nocodazole (1 µg/ml) was added and images of the cells at the permissive temperature (34°C) were captured for the indicated times. Inserts are enlarged twofold to show the appearance of GalT-YFP and VSVG-CFP in the ER exit sites. Scale bars: 10 µm. (B) Quantitative analysis of the time-dependent decrease in fluorescence intensity (FI) in a region of interest over the Golgi complex of the top cell in A. The line is a simple exponential fit with a rate of 1.23% per minute (R²=0.97). (C) Analysis of the ER export of VSVG-CFP and GalT-YFP in nocodazole-treated cells. Graph shows the time-dependent relative change in variance of fluorescence intensity in a region of interest over the cell in an area that excludes the pre-redistributed Golgi complex.