Table 2.
Kinetic parameters of M2 segment and M2–M3 linker mutants of the muscle AChRa
| α1-subunit mutation | Site of mutation | τdeactivation (ms) | τentry into desensitization (ms) |
|---|---|---|---|
| Wild type | — | 2.61 ± 0.11 (20/29) | 22.3 ± 3.4 (21/43) |
| L9′A | M2 segment | 29.5 ± 18.1 (0.472 ± 0.111) | 511 ± 115 (6/6) |
| 206 ± 68 (3/3) | |||
| L9′A + T–6′G | M2 segment + | 49.5 ± 0.6 (0.837 ± 0.070) | 518 ± 247 (5/5) |
| M1–M2 linker | 350 ± 49 (2/4) | ||
| S27′I | M2–M3 linker | 18.2 ± 3.2 (7/8) | 47.3 ± 13.1 (6/11) |
aAll errors are SEs. For some constructs, the number of exponential components required to achieve a good fit to the deactivation and/or desensitization time courses varied among patches, which complicated the direct comparison of data across different experiments. Hence, only the kinetic parameters corresponding to the most common type of fit are presented. For all data columns, fractions are presented for each construct: the numerator is the number of patches from which the time courses were best fit with the indicated number of exponential components, and the denominator is the total number of patches from which such time courses were recorded. Each time course was obtained from a different patch of membrane. —, Not applicable.