Figure 8.

Inactive Arf4 · GDP localizes to the ERGIC. (A) NRK cells were cotransfected with plasmids encoding wild-type Arf4-mCherry and the GDP-arrested mutant (T31N) of Arf4-GFP. Transfectants were imaged both before and after addition of 100 μM Exo1. Images correspond to single frames obtained immediately prior (t = 0′) or 10 min after Exo1 addition. Wild type (WT), but not the T31N mutant of Arf4-GFP, localizes to the Golgi complex; staining patterns for mutant and WT Arf4 become identical after Exo1 treatment. Bar, 10 μm. (B) NRK cells were transfected with plasmids encoding Arf4(T31N)-GFP. After treatment with carrier DMSO, 5 μg/ml BFA or 100 μM Exo1, cells were fixed and processed for IF as described in text. Insets show enlargement of boxed area. Right panels show merge signal from the enlarged area. Bar, 20 μm.