Parameters for 125I-ABA binding to CHO-hA1 membranes with or without 25 μM concentrations of allosteric enhancers, PD81723, or ATL525. Association kinetics from experiments conducted on the same day using the same pool of membranes and radioligand were optimally fit to a biexponential equation as described under Materials and Methods. The parameter values and S.E. are derived from least squares nonlinear regression fits.
| Bmax1 | Bmax2 | k1 | k2 | Bmax2 | |
|---|---|---|---|---|---|
| fmol | fmol | min−1 | min−1 | % of control | |
| Control | 1.49 ± 0.29 | 2.48 ± 0.16 | 0.375 ± 0.046 | 0.054 ± 0.002 | 100 |
| t½ (min) | 1.85 | 12.8 | |||
| PD81,723 | 1.39 ± 0.21 | 4.76 ± 0.61 | 0.24 ± 0.014 | 0.038 ± 0.005 | 193 |
| t½ (min) | 2.9 | 18.2 | |||
| ATL525 | 1.64 ± 0.08 | 3.97 ± 0.6 | 0.125 ± 0.018 | 0.015 ± 0.001 | 160 |
| t½ (min) | 5.5 | 46 |