FIGURE 4.

NBD-PS flip is inhibited by SC-azide and CCCP. Flow cytometry of NBD-PS flip at 2 °C with and without ATP or with the protonophore CCCP. Early log phase cells (A₆₀₀ = 0.2-0.4) were treated with SC-azide or with 50 μm CCCP for 10 min at 30 °C, prior to labeling with 10 μm NBD-PS at 2 °C for 1 h. Strains were the same as in Fig. 1. Data are the mean of at least three independent experiments, and the error bars represent the S.D. between experiments.