TABLE 3

ACh potency and allosteric model parameter estimates for interaction with 4-phenylpyridine-2-ones and 6-phenylpyrimidin-4-one at the M1 mAChR for three different signaling pathways in FlpInCHO-hM1 cells

For allosteric model analysis, ACh concentration-response curves, established in the absence or presence of each modulator, were fitted to eq. 3. The initial increase in ERK1/2 phosphorylation data were used (with the decreasing phase removed) for the purpose of the ERK1/2 analysis. Data are the mean ± S.E.M. of 4–15 independent experiments with repeats in duplicate. Data were analyzed by one-way ANOVA with a Newman-Keuls post hoc test to compare all groups. Results of the statistical tests are shown in Fig. 9.

BQCAMIPS1674MIPS1745MIPS1780
ERK1/2IP1βarr2ERK1/2IP1βarr2ERK1/2IP1βarr2ERK1/2IP1βarr2
pEC50a7.19 ± 0.135.73 ± 0.055.50 ± 0.077.54 ± 0.115.81 ± 0.085.17 ± 0.077.16 ± 0.085.67 ± 0.085.28 ± 0.137.24 ± 0.085.47 ± 0.095.18 ± 0.12
pKBb4.784.784.784.454.454.454.504.504.504.884.884.88
Logαc2.94 ± 0.201.60 ± 0.091.37 ± 0.120.64 ± 0.461.06 ± 0.08NM2.58 ± 0.252.11 ± 0.121.62 ± 0.202.74 ± 0.252.49 ± 0.152.36 ± 0.15
LogτBd1.18 ± 0.09−0.46 ± 0.12−0.31 ± 0.120.14 ± 0.14−3NM1.15 ± 0.090.07 ± 0.05−0.36 ± 0.141.75 ± 0.060.78 ± 0.050.14 ± 0.07
  • NM, no modulation (NAL effect).

  • a Negative logarithm of the ACh EC50 value.

  • b Negative logarithm of the binding affinity value determined previously in Mistry et al. (2016), and constrained as a constant in the current analysis.

  • c Logarithm of the cooperativity between ACh and the allosteric modulator, derived using eq. 2.

  • d Logarithm of the operational efficacy parameter of the allosteric modulator, derived using eq. 2; or constrained to −3 where no intrinsic efficacy of the allosteric modulator was observed.