Kinetic Parameters of a Set of Wild-type AChRs and Naturally Occurring Mutants
| Construct | τdeactivation (ms)a | t1/2, desensitization (ms)b | Paired-pulse τrecovery (ms)c | Train τrecovery (ms)d |
| ɛP121L (adult, mouse) | 0.37 ± 0.02 (7) | 66 ± 10 (9) | 101 ± 18 (6) | NDe |
| δD59K (adult, mouse) | 0.92 ± 0.08 (10) | 38 ± 7 (7) | 71 ± 5 (3) | ND |
| wild-type/ɛ (adult, mouse) | 0.98 ± 0.06 (25) | 22 ± 3 (13) | 306 ± 19 (5) | 500 (6) |
| wild-type/γ (fetal, mouse) | 4.5 ± 0.5 (10) | 31 ± 12 (3) | 290 ± 33 (4) | 167 (4) |
| βV266M (adult, mouse) | 5.4 ± 0.1 (10) | 38 ± 6 (4) | 279 ± 26 (2) | 167 (4) |
| ɛL221F (adult, mouse) | 6.6 ± 0.4 (17) | 34 ± 12 (4) | 466 ± 21 (4) | 1,333 (8) |
| αS269I (adult, mouse) | 9.2 ± 0.7 (10) | 20 ± 4 (9) | 552 ± 29 (5) | 667 (4) |
| ɛL269F (adult, mouse) | 19 ± 2 (11) | 28 ± 5 (10) | 1,830 ± 170 (5) | 1,000 (7) |
| ɛT264P (adult, mouse) | 21 ± 1 (29) | 99 ± 10 (11) | 742 ± 37 (2) | 1,000 (8) |
| Construct | τdeactivation (ms)a | t1/2, desensitization (ms)b | Paired-pulse τrecovery (ms)c | Train τrecovery (ms)d |
| ɛP121L (adult, mouse) | 0.37 ± 0.02 (7) | 66 ± 10 (9) | 101 ± 18 (6) | NDe |
| δD59K (adult, mouse) | 0.92 ± 0.08 (10) | 38 ± 7 (7) | 71 ± 5 (3) | ND |
| wild-type/ɛ (adult, mouse) | 0.98 ± 0.06 (25) | 22 ± 3 (13) | 306 ± 19 (5) | 500 (6) |
| wild-type/γ (fetal, mouse) | 4.5 ± 0.5 (10) | 31 ± 12 (3) | 290 ± 33 (4) | 167 (4) |
| βV266M (adult, mouse) | 5.4 ± 0.1 (10) | 38 ± 6 (4) | 279 ± 26 (2) | 167 (4) |
| ɛL221F (adult, mouse) | 6.6 ± 0.4 (17) | 34 ± 12 (4) | 466 ± 21 (4) | 1,333 (8) |
| αS269I (adult, mouse) | 9.2 ± 0.7 (10) | 20 ± 4 (9) | 552 ± 29 (5) | 667 (4) |
| ɛL269F (adult, mouse) | 19 ± 2 (11) | 28 ± 5 (10) | 1,830 ± 170 (5) | 1,000 (7) |
| ɛT264P (adult, mouse) | 21 ± 1 (29) | 99 ± 10 (11) | 742 ± 37 (2) | 1,000 (8) |
Deactivation time constants estimated from mono-exponential fits. The numbers in parentheses indicate the number of low-frequency trains of 0.8-ms ACh pulses analyzed. Each train consisted of at least 10 pulses, the responses to which were averaged and fitted. Average values across trains are given as mean ± SE.
Desensitization half-times. In some cases, the time course of entry into desensitization was best fitted with two, rather than one, exponential components. Hence, to facilitate the comparison, the parameters of these fits (whether single or double exponential) were used to numerically solve for the corresponding desensitization half-times (that is, the time taken for the current decay to be half-complete). The numbers in parentheses indicate the number of analyzed responses. Average values are given as mean ± SE.
Recovery from desensitization time constants estimated from the response to paired-pulse protocols. The numbers in parentheses indicate the number of independent experiments analyzed to generate the plots in Fig. 3 C.
Recovery from desensitization time constants estimated from the fitting of the plots in Fig. 5 as described in Materials and methods. The best-fit values were identified by manually adjusting the unknown parameter, and standard errors were not estimated.
Not determined. This parameter was estimated only for wild-type and slow-channel mutant AChRs.