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. 2000 Oct 1;116(4):535–546. doi: 10.1085/jgp.116.4.535

Figure 6.

Figure 6

Fast-gating properties of heterodimers after MTSEA modification. (A) Single-channel recording traces of K165C*, K165-K165C*, and K165 channels. Membrane potential, −40 mV. Dotted lines are zero-current level. (B) P o-V curves derived from single-channel recordings (n = 3–7). Solid curves are Boltzmann curves for K165 (○) and K165C* (•) channels, while the dashed curve is simply the average of the two solid curves. (□) The measured P o of the heterodimers (average of K165-K165C* and K165C*-K165). (C) Single-channel recordings of the heterodimer K165C*-K165 at three different voltages. Open probabilities shown on the right were calculated from >40-s continuous recordings, including the three traces shown at left. (D) Comparison of the measured state probabilities (bars) with the expected state probabilities (circles). (•) Calculated from the averaged P o of the heterodimer according to (binomial distribution). (○) Calculated according to , assuming distinct P o's for two pores (multinomial distribution). The open probabilities were taken from the P o's of the homodimers at the corresponding voltages shown in B. Statistical analysis showed significant difference (P < 0.01, one sample t test, SPSS 8.0; SPSS, Inc.) between the measured probabilities of the M level and the expected values derived from the binomial model in all three voltages. The comparisons of the measured probabilities with the expected values from the multinomial model, however, showed no difference (P > 0.01).