Figure 2.

Baf A1 inhibits the BFA-induced redistribution of Golgi glycosyltransferases as measured by processing of the VSV tsO45 mutant G protein retained in the ER at the restrictive temperature (39.5°C). Chinese hamster ovary cells were infected with VSV tsO45 and, after virus adsorption, cultured for 3 h at 39.5°C in the presence or absence of Baf A1. The cells were pulse-labeled at 39.5°C with ³⁵S-methionine/cysteine and then either transferred directly on ice or chased for 45–90 min at 39.5°C in the presence of different concentrations of BFA (0.2 or 5 μg/ml). The pulse–chase of Baf A1-pretreated cells was performed in the continuous presence of the drug. The tsO45 G protein was immunoprecipitated from cell lysates and analyzed, either undigested or after digestion with endo H, by SDS-PAGE. The amount of conversion of the G protein to the endo H-resistant form was quantitated as described in MATERIALS AND METHODS. White columns, Control cells; black columns, Baf A1-treated cells.