Figure 7.

Effect of the actin filament disrupting agent cytD on transport of C₆-NBD-SM (A) and -GlcCer (B) from SAC. C₆-NBD-lipid was accumulated into SAC as described in MATERIALS AND METHODS. After abolishing the remaining BC-associated NBD fluorescence with sodium dithionite, cells were treated with 10 μg/ml cytD at 4°C for 30 min. Then they were washed and kept in HBSS at 4°C until use (<30 min; t = 0, before chase) or, alternatively, warmed to 37°C and incubated in back-exchange medium in the presence of cytD for 20 min. Cells were then rapidly cooled and kept on ice until use (<30 min). The percentage of NBD-lipid-labeled BCP (inset) and the distribution of the BCP-associated NBD-lipid (i.e., BC, SAC, or both) before (white bars) and after the chase from SAC (cross-hatched bars) was determined as described in MATERIALS AND METHODS. Data are expressed as mean ± SEM of at least two independent experiments carried out in duplicate.