Table 3. ELIC WT and mutant channel properties by patch-clamping giant liposomes composed of 25 mole% POPG (n = 3–7, ± SD).
Shown are weighted time constants (τ) for desensitization and currents 20 s after application of 30 mM cysteamine normalized to peak response. Also shown are activation time constants and EC50 of cysteamine response. Light gray indicates mutant values which are significantly different from WT (blue) (**p<0.01, *p<0.05).
| Desensitization | Activation | Cysteamine response | ||
|---|---|---|---|---|
| Weighted τ (s) | Norm current at 20 s | τ (ms) | EC50 (mM cysteamine) | |
| WT | 1.95 ± 0.48 | 0.100 ± 0.041 | 134 ± 50 | 5.1 ± 1.2 |
| R117Q | 1.49 ± 0.40 | 0.060 ± 0.020 | 54 ± 40 * | 3.3 ± 0.9 * |
| R123Q | 1.20 ± 0.39 | 0.067 ± 0.015 | 112 ± 65 | 3.7 ± 0.9 |
| R286Q | 1.67 ± 0.24 | 0.091 ± 0.023 | 106 ± 34 | 4.3 ± 0.4 |
| R299Q | 2.2 ± 0.17 | 0.074 ± 0.008 | 71 ± 27 | 4.7 ± 0.3 |
| R301Q | 0.66 ± 0.28 ** | 0.045 ± 0.017 ** | 72 ± 15 | 5.2 ± 0.8 |
| R117Q/R299Q | 1.13 ± 0.24 * | 0.025 ± 0.004 ** | 54 ± 26 * | 2.4 ± 0.7 ** |
| R123Q/R299Q | 1.66 ± 0.17 | 0.041 ± 0.005 ** | 74 ± 35 | 3.7 ± 0.6 |
| R286Q/R299Q | 2.08 ± 0.65 | 0.103 ± 0.032 | 92 ± 27 | 4.7 ± 1.5 |
| R301Q/R299Q | 0.45 ± 0.28 ** | 0.030 ± 0.017 ** | 71 ± 21 | 3.9 ± 0.9 |
| L238A | 5.90 ± 1.37 ** | 0.374 ± 0.045 ** | 113 ± 51 | 4.9 ± 1.1 |