EGFP-wt hM1 | EGFP-W405A | EGFP-W405F | EGFP-W400A | EGFP-W400F | ||||||
---|---|---|---|---|---|---|---|---|---|---|
pKd,i,xpα | pEC50,diss (Emax, %) | pKd,i,x pα | pEC50,diss (Emax, %) | pKd,i,x pα | pEC50,diss (Emax, %) | pKd,i,x pα | pEC50,diss (Emax, %) | pKd,i,x pα | pEC50,diss (Emax, %) | |
[3H]NMS Bmaxa | 10.02 ± 0.03 445 ± 35a | 10.27 ± 0.04 400 ± 75a | 10.28 ± 0.03 910 ± 125a | 10.04 ± 0.01195 ± 15a | 10.04 ± 0.04 395 ± 45a | |||||
Atropine | 9.19 ± 0.03 | 9.30 ± 0.08 | 9.57 ± 0.01 | 9.35 ± 003 | 9.03 ± 0.06 | |||||
Pirenzepine | 8.03 ± 0.08 | 7.73 ± 0.01 | 8.24 ± 0.04 | 7.65 ± 0.10 | 7.89 ± 0.23 | |||||
Carbachol | 4.89 ± 0.14 | 5.58 ± 0.19 | 5.18 ± 0.01 | 4.68 ± 0.12 | 4.53 ± 0.12 | |||||
Gallamine | 5.04 ± 0.06 | 3.94 ± 0.07 (100) | 4.88 ± 0.06 | 4.00 ± 0.04 (100) | 4.74 ± 0.02 | 3.82 ± 0.05 (100) | 3.96 ± 0.03 | 2.35 ± 0.03 (100)b | 4.10 ± 0.07 | 3.25 ± 0.07 (80 ± 5) |
-1.12 ± 0.02c | -0.89 ± 0.02c | -0.78 ± 0.07c | -1.21 ± 0.04c | -0.92 ± 0.07c | ||||||
Brucine | 4.59 ± 0.02d | 4.49 ± 0.02 (100) | N.A.e | 5.02 ± 0.03 (100) | N.A.e | 4.79 ± 0.03 (100) | N.A.e | 3.31 ± 0.06 (77 ± 4) | N.A.e | 3.68 ± 0.05 (85 ± 3) |
-0.10 ± 0.02c |
N.A., not applicable; wt, wild type.
↵a Maximal densities in [3H-NMS] binding sites (Bmax, fmol/106 cells) are from saturation experiments.
↵b EC50,diss is from curve fitting to eq. 8 with Emax,diss constrained to 100%.
↵c Cooperativity factor (negative logarithm).
↵d EC50,diss was used for curve fitting according to eq. 5 because of nearly neutral cooperativity (Data Analyses).
↵e Not applicable. Over a 1–300 µM concentration range, brucine did not significantly modify equilibrium [3H]NMS binding at the mutants.