Fractional subconductance value induced by calcins on single RyR1 channels. RyR1 channel from rabbit skeletal muscle SR vesicles was reconstituted in lipid bilayers and recorded and analyzed as described in Materials and methods. (A) Single RyR1 channel in the absence of calcin is presented as control. (B–I) The eight calcins were added separately into the cis (cytosolic) chamber at the indicated concentration. c represents the zero current level when the channel is in the fully closed state, whereas s and o display the subconductance state and full opening of the channel, respectively. Current histograms from 10,000–30,000-ms segments of channel activity are shown at the right side of the traces for each calcin. The number of experiments varied for each calcin. Imperacalcin, maurocalcin, and hadrucalcin: n = 12, 8, and 5 different channels. All other calcins were tested at least two or three times.