FIGURE 4.

Single Ca²⁺ release channel currents through WT and the mutant RyR1s. Single-channel currents were recorded at a holding potential of −40 mV (cis) in a symmetrical solution containing 250 mm cesium methanesulfonate buffered with 20 mm HEPES/Tris, pH 6.8. Free Ca²⁺ was set at 0.1 mm to optimally activate the channel. A, representative traces of single-channel currents through WT and the mutant RyR1 channels. The conductance level of the closed state is shown by a short line on the left side of each current recording. B, mean P_o of WT and the mutant channels. C, the full open conductance of WT and the mutant channels. Data are means ± S.E. (n = 6–11). *, p < 0.05 compared with WT.