A, representative single channel currents recorded from cells expressing wild-type (Kir6.2 + SUR1) or Kir6.2ΔN2−30 + SUR1 channels, fc = 1 kHz. c and o indicate the closed and open channel levels. B, unconditional open and closed time distributions from the records shown in A, using log binning. Open times were well fitted by single exponential distributions for both wild-type (TO = 9.5 ms) and ΔN2-30 (TO = 11.9 ms). Two time constants (TC1 = 5.9 ms, relative fraction = 0.6; TC2 = 71.9 ms, relative fraction = 0.4) were necessary to describe wild-type closed distributions, but a single time constant (TC1 = 4.0 ms) was sufficient to describe ΔN2-30 channel closed time distribution.