Figure 5. Effect of phospholipids on the K_ACh channel openings in inside-out patches.

A, the current tracings were taken from experiments such as those shown in Fig. 4A and shown on an expanded time scale. The left portion shows channel openings in the presence of GTPγS alone, and the right portion shows the effect of adding a phospholipid to the same inside-out patch. The increase in the open time duration can be discerned easily for all phospholipids. B, a gating scheme for channels activated by GTPγS alone and a scheme for channels activated by GTPγS and a phospholipid were used to obtain transition rates between states after idealization of real data. Channel currents were simulated using these rates. A simulated current with GTPγS, and a current with GTPγS and 100 μM PE or 50 μM PIP are shown for comparison with actual data in A.