Fig. 4.

SR channel behavior of the most commonly observed conductance from bilayers containing a single-channel protein. A: representative current recordings from a bilayer containing a single ion channel defined by a unitary conductance similar to that of the channel shown in Fig. 2. C and O, channel closed and open states, respectively. Records were obtained in 300 mM Cs⁺ with V = −25 mV. Data were low-passed at 1 and digitized at 10 kHz. B: the all-points amplitude histogram from the records shown in A has 2 modes, which correspond to the close and open states (left). The difference between the modes renders a unitary amplitude of 8.3 pA. Open (middle) and closed (right) time distributions could be well fitted with 3 exponentials, with a solid line giving the composite fit. On top of each peak, the time constants corresponding to each component are given in ms. Number of events: 1,210 (openings) and 2,015 (closures).