Single-Channel and Macroscopic Parameters of Homomeric Wild-Type KATP Channels
| Parameter . | Obtained from . | Connected tetramers . | Unconnected tetramers . |
|---|---|---|---|
| IC50 | macroscopic data | 14.5 ± 2.5 μM | 8.4 ± 2.9 μM |
| h | macroscopic data | 1.42 ± 0.07 | 1.22 ± 0.16 |
| PO | single-channel data | 0.75 ± 0.04 | 0.33 ± 0.10 |
| τB(0) | single-channel data | 127 ± 18 ms | 20.7 ± 6.0 ms |
| a | τO(0), τB(0) | 0.59 ± 0.02 ms−1 | 0.54 ± 0.07 ms−1 |
| b | τF(0) | 2.8 ± 0.1 ms−1 | 2.7 ± 0.3 ms−1 |
| c | τO(0), τB(0) | 0.009 ± 0.001 ms−1 | 0.06 ± 0.02 ms−1 |
| F | a and b | 0.21 ± 0.03 | 0.20 ± 0.05 |
| E0 | PO | 0.12 ± 0.02 | 1.83 ± 1.01 |
| KO,WT | τB(0)/τB([ATP]) | 3.1 ± 0.2 mM−1 | 3.2 ± 0.2 mM−1 |
| KO,WT | τO([ATP]) | 3.8 ± 0.9 mM−1 | 3.2 ± 0.2 mM−1 |
| mWT | τB(0)/τB([ATP]) | 2.8 ± 0.1 | 2.7 ± 0.1 |
| mWT | τO([ATP]) | 2.4 ± 0.1 | 2.5 ± 0.1 |
| Parameter . | Obtained from . | Connected tetramers . | Unconnected tetramers . |
|---|---|---|---|
| IC50 | macroscopic data | 14.5 ± 2.5 μM | 8.4 ± 2.9 μM |
| h | macroscopic data | 1.42 ± 0.07 | 1.22 ± 0.16 |
| PO | single-channel data | 0.75 ± 0.04 | 0.33 ± 0.10 |
| τB(0) | single-channel data | 127 ± 18 ms | 20.7 ± 6.0 ms |
| a | τO(0), τB(0) | 0.59 ± 0.02 ms−1 | 0.54 ± 0.07 ms−1 |
| b | τF(0) | 2.8 ± 0.1 ms−1 | 2.7 ± 0.3 ms−1 |
| c | τO(0), τB(0) | 0.009 ± 0.001 ms−1 | 0.06 ± 0.02 ms−1 |
| F | a and b | 0.21 ± 0.03 | 0.20 ± 0.05 |
| E0 | PO | 0.12 ± 0.02 | 1.83 ± 1.01 |
| KO,WT | τB(0)/τB([ATP]) | 3.1 ± 0.2 mM−1 | 3.2 ± 0.2 mM−1 |
| KO,WT | τO([ATP]) | 3.8 ± 0.9 mM−1 | 3.2 ± 0.2 mM−1 |
| mWT | τB(0)/τB([ATP]) | 2.8 ± 0.1 | 2.7 ± 0.1 |
| mWT | τO([ATP]) | 2.4 ± 0.1 | 2.5 ± 0.1 |
n = 5 for macroscopic data; n = 10 for single-channel data. Values of KO,WT and mWT were obtained by fitting the MWC model (Eq. 11 for burst ratios and Eq. S4 for open times) to the mean values obtained from three to five experiments. All other parameters were calculated from 10 experiments.