Allosteric properties of THA at M2 and M3 receptors
The parameters pKapp and Hill slope (nH) represent best-fit values ± S.E. from global curve fitting to the combined data of three or more assays. Statistical significance was determined by F test, either between or within data sets (see Materials and Methods). The between-set P values shown are for comparisons with the immediate parental receptor; for example, hM2′ was compared with hM2, while hM2′C96A, C176A was compared with hM2′. When nH was found to be significantly (P < 0.05) different from the parental receptor (or when there was no parental receptor), a global F test was also carried out to determine whether nH differed from the standard (unit) slope.
Receptor | pKapp and F-test | Hill slope (nH) and F tests | ||||||
|---|---|---|---|---|---|---|---|---|
| pKapp | vs Parental | nH | vs Parental | vs Unity | ||||
| hM2 | 5.38 ± 0.02 | 1.89 ± 0.11 | <0.0001 | |||||
| hM2′ | 5.30 ± 0.02 | 0.0013 | 2.07 ± 0.13 | 0.3203 | ||||
| hM2, 6.5% labeling | 5.34 ± 0.02 | 0.1441 | 1.67 ± 0.12 | 0.2686 | ||||
| hM2′ C96A C176A | 4.73 ± 0.08 | <0.0001 | 1.31 ± 0.23 | 0.0129 | 0.1715 | |||
| hM2 C413A, C416A | 5.41 ± 0.02 | 0.2778 | 1.74 ± 0.11 | 0.4021 | ||||
| hM3 | 4.90 ± 0.02 | 1.90 ± 0.13 | <0.0001 | |||||
| hM3 C141A, C221A | 5.23 ± 0.09 | 0.0087 | 0.79 ± 0.10 | <0.0001 | 0.1380 | |||
| hM3 C517A, C520A | 5.01 ± 0.04 | 0.0461 | 1.84 ± 0.21 | 0.7913 | ||||
| rM3′ | 4.82 ± 0.02 | 2.05 ± 0.16 | <0.0001 | |||||
| rM3′, 8.2% labeling | 4.86 ± 0.06 | 0.5713 | 1.65 ± 0.32 | 0.3308 | ||||
| rM3′ C140A, C220A | 5.25 ± 0.09 | 0.0015 | 0.83 ± 0.11 | <0.0001 | 0.1987 | |||