Figure 9.

BFA-Induced Release of COPI Coat Proteins and AtArf1p from Tobacco BY-2 Membranes, and Their Reassociation after BFA Removal Analyzed by Protein Gel Blotting.

(A) BY-2 cells were incubated in the presence of 10 μg/mL BFA, and samples were removed at the times indicated. The cells were homogenized and then centrifuged to separate total membranes from the cytosol as described in Methods. Both fractions were probed for gains or losses in coat proteins as indicated. The ER marker BiP was included as a standard lumenal protein.

(B) BY-2 cells were treated with 10 μg/mL BFA for 20 min, washed twice, and then incubated in fresh culture medium. Samples were removed at the times given and processed as in (A). All lanes contained equal amounts of proteins (30 μg). Lane C, untreated control cells.