Fig. 3.

Effects of cytosolic Ca²⁺ on type 1 ryanodine receptor-wild type (RyR1-WT) and mutant channel open probability (P_o). A–C: representative single-channel currents of RyR1-WT (A), RyR1-Q3970E (B), and RyR1-Q3970K (C) were recorded as downward deflections from the closed state (c–) in 250 mM symmetrical KCl at −20 mV with 2 µM sarcoplasmic reticulum (SR) luminal Ca²⁺ and the indicated cytosolic Ca²⁺ concentrations. D: Ca²⁺ dependence of RyR1-WT, RyR1-Q3970E, and RyR1-Q3970K channel open probabilities. Data are the mean ± SE of 3–21 recordings. Inset: open probabilities of WT and Q3970K in a logarithmic scale. [WT data in D were obtained from Xu et al. (31) under recording conditions used in the present report.]