Fig. 5

Ca²⁺-dependence and activation of F-ATP synthase channels by Bz-423. a Power spectrum area (PSA) and open probability (Po) of F-ATP synthase channels were calculated from five independent experiments in the absence of activators (control), after addition of 3 mM Ca²⁺ alone or following the addition of both 3 mM Ca²⁺ and 0.15 mM Bz-423. Zero values are indicated with black and blue dotted lines for PSA and Po, respectively. Data shown are mean ± SEM. Statistical significance of differences was assessed with the Mann–Whitney test (*p ≤ 0.05, **p ≤ 0.01). b Mean and maximal conductance (G_mean and G_max) were calculated for the same experiments shown in panel a. c Current traces elicited after addition of 3 mM Ca²⁺ alone or after further addition of 0.15 mM Bz-423 (V_cis = –60 mV, G_max = 500 pS) from one representative experiment of five. The closed state is denoted with C, the most frequent subconductance state with an asterisk, and the maximal open state with O. d Current distribution of 30 s-recordings from experiments similar to the one reported in panel c. In the presence of Ca²⁺ alone, flickering openings may be observed as a small peak in the histogram (arrow), while in the presence of Bz-423, a complex distribution with multiple peaks at higher conductance values (400 and 500 pS) is detectable. e PSA and Po of F-ATP synthase channels as a function of the Ca²⁺ concentration in the presence of 0.15 mM Bz-423; PSA and Po distributions were fitted with the Hill equation (n = 1.37 ± 0.29, R² = 0.992; n = 1.17 ± 0.16, R² = 0.997, respectively). Data were obtained from 23 independent experiments and are shown as mean ± SEM. f G_mean and G_max of F-ATP synthase channels as a function of the Ca²⁺ concentration from the same experiments shown in panel e. The source data underlying panels a, b, e, f are provided as a Source Data file