Figure 3.
Single channel open probability for type I and type III InsP3R as a function of Ca2+ concentration. a, Channel activity for type III InsP3R in the presence of 2 μM InsP3, 0.5 mM ATP, 0.5 mM EGTA, 2 μM ruthenium red, and at 0 mV. Channel openings are shown as downward deflections. b, Single channel open probability of type I InsP3R (circles) and type III InsP3R (triangles). Data points for type I InsP3R were taken from ref.17. Data for three experiments are shown for type III InsP3R. Individual points with error bars are the mean ± s.e.m. for n = 2 (1 and 10 μM Ca2+) or n = 3 (0.01 and 0.1 μM Ca2+).