Figure 6.

ɛCOP is more sensitive to BFA treatment than is ARF1. A, Time-lapse confocal micrographs demonstrate the effect of BFA treatment on a live tobacco epidermal cell coexpressing ɛCOP-YFP and ARF1-GFP. Representative images are shown with the time(s) indicated in the top right corner. The first image in the sequence (labeled 0.0) was taken after a 45-min pretreatment with latrunculin B and a subsequent incubation of 5 min with BFA. The images show that ɛCOP-YFP fluorescence is released from the Golgi (arrow) prior to the release of ARF1-GFP in the cytosol. Scale bar = 5 μm. The fluorescence of the punctate structures relative to that of the cytosol was measured for both ARF1-GFP and ɛCOP-YFP in each frame of the time lapse with (B) and without (C) BFA treatment. The RPSF is given as a percentage of the ratio between fluorescence intensity values (arbitrary units) measured in the punctate structure and the sum of intensity values for the cytosol and punctate structure (see “Materials and Methods”).