Figure 3. Effect of DIDS on purified RyR1.

(A) Single-channel activity of purified RyR1 was recorded with 10 μM Ca²⁺ without (control) or with DIDS (10–100 μM). Single-channel currents are shown as downward deflections from the closed level (indicated by c). The holding potential was −30 mV. Note that the extent of channel activation by 10 μM DIDS was considerably lower in purified RyR1 compared with native RyR1 in Figure 1. (B) Native RyR1 or purified RyR1 was activated or modified by serial addition of 10 μM Ca²⁺, 3 mM caffeine, 10 μM ryanodine and 5 μM Ruthenium Red. Note that the patterns of the activation and modification by Ca²⁺, caffeine, ryanodine and Ruthenium Red are similar between native and purified RyR1s (Supplementary Table 1).