Figure 8.

CT transport to the Golgi complex is inhibited by Arf1(Q71L) and Sar1(H79G). Vero cells were injected with a mixture of GFP and either Arf1(Q71L) (A–D) or Sar1(H79G) (E–H) expression plasmids. After a 5-h period of protein expression, the cells were allowed to bind either CT-B-FITC or unlabeled holotoxin and internalize for 40 min at 37°C. Injected cells (identified by GFP expression shown in A, C, E, and G) displayed internalization of the toxin to early endosomes but not to the Golgi (outlined cells in B, D, F, and H). An apparent accumulation of toxin at the cell surface of injected cells was also often noted and may reflect a slight reduction in initial internalization. Bars, 20 μm.