Properties of α 7 AChR cysteine mutants of the β 1-loop2-β 2 region
The EC50 and Imax measurements for each receptor mutation represent mean values (± S.E.M.) from at least three separate experiments. For dose-response relationships that did not reach a plateau, EC50 and Imax values represent a lower limit. Mutants that had an MTSEA effect (indicated by +) had a statistically significant different EC50 after MTSEA exposure (paired t test, P < 0.05).
Mutant | Before MTSEA Exposure | MTSEA Effect? | After MTSEA Exposure | Modification Rate | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| ACh EC50 | Imax | ACh EC50 | Imax | Imax (of control) | -ACh | + ACh | ||||||
| μM | μA | μM | μA | % | M-1s-1 (n) | |||||||
| C115A/L247T | 2.4 ± 0.1 | 5.0 ± 0.7 | - | |||||||||
| M37C | 2.3 ± 0.3 | 0.4 ± 0.2 | + | >1000a | 0.05 ± 0.03a | 13a | 4.7 ± 1.1 × 103 (8) | 6.3 ± 1.3 × 102 (5) | ||||
| M40C | 2.6 ± 0.4 | 1.5 ± 0.3 | + | 22 ± 5.8 | 1.3 ± 0.4 | 87 | 2.7 ± 0.8 × 104 (6) | 3.2 ± 0.8 × 103 (4) | ||||
| D41C | 9.1 ± 2.0 | 0.04 ± 0.01 | - | |||||||||
| V42C | 7.7 ± 0.4 | 1.0 ± 0.3 | + | 46 ± 11 | 0.7 ± 0.4 | 70 | 1.2 ± 0.4 × 102 (3) | 1.6 ± 0.7 × 101 (4) | ||||
| D43C | 46 ± 3.4 | 0.5 ± 0.1 | + | 54 ± 4.4 | 0.5 ± 0.2 | 100 | 3.5 ± 0.4 × 101 (3) | 7.1 ± 0.9 × 101 (3) | ||||
| E44C | 12 ± 1.3 | 5.6 ± 0.7 | + | 27 ± 1.0 | 4.9 ± 0.08 | 88 | 6.3 ± 2.4 × 104 (7) | 4.9 ± 1.1 × 103 (4) | ||||
| K45C | 71 ± 22 | 3.5 ± 0.2 | + | 45 ± 7.3 | 3.5 ± 0.4 | 100 | 2.1 ± 5.3 × 104 (5) | 5.9 ± 1.1 × 104 (4) | ||||
| N46C | 15 ± 0.6 | 0.04 ± 0.01 | - | |||||||||
| Q47C | 60 ± 11 | 1.5 ± 0.1 | + | 39 ± 7.6 | 1.2 ± 0.1 | 80 | 2.5 ± 1.2 × 101 (5) | 1.0 ± 0.2 × 103 (6) | ||||
| V48C | 11 ± 2.1 | 4.1 ± 0.9 | - | |||||||||
| T50C | 9.3 ± 0.4 | 0.03 ± 0.01 | - | |||||||||
| T51C | 4.3 ± 0.3 | 1.3 ± 0.5 | - | |||||||||
| N52C | 13 ± 3.0 | 0.4 ± 0.2 | + | >1000a | 0.02 ± 0.01a | 5a | 6.8 ± 3.5 × 101 (4) | 1.7 ± 0.3 × 103 (3) | ||||
| I53C | 1.6 ± 0.1 | 5.1 ± 0.6 | - |
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↵ a Dose-response relationships that did not reach a plateau.