CLPB mutants show impaired ATPase and disaggregase activity and exhibit a dominant-negative effect on WT CLPB. Purified CLPB protein was used to measure ATPase activity of the indicated CLPB variants tested in isolation (A); disaggregase activity of the indicated CLPB variants tested in isolation (B); ATPase activity of WT CLPB when mixed 1:1 with WT CLPB or CLPB variants (C); and disaggregase activity of WT CLPB when mixed 1:1 with WT CLPB or CLPB variants (D). In (C-D), the dotted line represents 50% of WT CLPB activity. Data represent 3 independent experiments. *P < .05, **P < .01, ***P < .001, ****P < .0001, 1-way ANOVA. In (A-B), comparison was made with WT CLPB activity. A comparison was made with values representing 50% of WT activity (C-D).