Figure 1.

The β₁ subunit alters the single-channel gating kinetics in both the absence and presence of Ca²⁺ _i. (A) Currents recorded from single α and α+β₁ channels in 0 Ca²⁺ _i. A continuous record in each case was cut into the five presented traces. The β₁ subunit increases both burst duration and the duration of the gaps between bursts. The average P _os for the entire record from which each excerpt was obtained were: 0.00056 for the α channel and 0.0039 for the α+β₁ channel. (B) Bursts from α and α+β₁ channels presented on a faster time base. (C) Currents recorded from α and α+β₁ channels in 1.8 μM Ca²⁺ _i. The traces were filtered at 4 kHz for display in this and subsequent figures, while the filtering for the analysis carried out in this paper was typically 10 kHz. Membrane potential: +30 mV; α channel, C92; α+β₁ channel, C87.