Scheme I accounts for the single-channel currents over a range of voltages and at two different temperatures. (A and B) Scheme I with the estimated rate constants and noise values for a representative channel at different voltages was used to simulate single-channel currents at the indicated voltages and at 20°C. A comparison of these simulated single-channel currents with the experimental single-channel currents in Fig. 1 (A and B) shows that scheme I accounts for the major features of the single-channel data at 20°C over the range of voltage. The boxed area (A) in the trace at 60 mV indicates a short segment of recording that is amplified in B. (C) Single-channel currents simulated with scheme I account for the major features of the single-channel data at 20 and 30°C (compare with Fig. 11 A).