Figure 7.

Exo1 causes rapid loss of Arfs from Golgi membranes but leads to eventual concentration of GFP-GBF1 and class II Arfs at the ERGIC. (A) NRK-GFP-GBF1 cells transfected with plasmids encoding Arfs tagged with mCherry were treated with carrier DMSO or 100 μM Exo1 and imaged for 20 min as described in Materials and Methods. Images correspond to single frames captured at the indicated times. Data obtained with Arf3 and Arf5 are provided as Supplemental Material. Bar, 10 μm. (B) NRK cells were treated with DMSO (a–d) or 100 μM Exo1 (e–h) for 20 min and then processed for double-label IF by using antibodies to the indicated markers. Paired panels a, b and e, f display green, red channels from the same area of cells transfected with plasmids encoding Arf4-GFP. Insets in c and g display images obtained with antibody to the ERGIC marker Molly 6. GBF1 and Arf4-GFP concentrate on ERGIC structures devoid of COPI and the Golgi marker Man II. Images representative of four experiments. Bar, 20 μm.