Fig 8.

Effect of substrates on ATPase activity. (A) We performed assays of ATPase activity with purified PM vesicles from the WT double-copy strain in the presence of transport substrates as described in Fig. 5 using 3 mM ATP in each reaction. Plots for each compound are shown. At least two curves were generated for each compound. (B) ATPase activity of the V656L mutant. ATPase activities were determined as described in Fig. 5. Data represent determinations from two independent PM vesicle preparations from each strain. (A) ATPase activity as a function of ATP concentration (0 to 3 mM). n = 3. Error bars indicate the standard error. (C) The effect of clo (1.78 to 12.5 μM) on ATPase activity is shown using 3 mM ATP in each reaction. ■, WT; ▲, V656L mutant. Inhibition curves are the averages of 3 independent experiments, including two different PM preparations of the V656L mutant. (D) Effect of tamoxifen on V656L mutant ATPase. The conditions are identical to those described in panel C except that tamoxifen was added to the reaction mixes.