Dissociation constant of adrenergic ligands for the binding to wild type and mutant adrenergic receptors
| Receptors | Ligands | |||||||
|---|---|---|---|---|---|---|---|---|
| no GTP | with GTP | |||||||
| PIN | ISO | EPI | mape | PIN | ISO | EPI | mape | |
| pM | μM | pM | μM | |||||
| Wild-type β2AR | 263 (± 14) | 0.07 (± 0.01) | 0.29 (± 0.06) | 25.6 (± 2) | 244 (± 12) | 0.21 (± 0.03) | 0.9 (± 0.16) | 38.5 (± 0.74) |
| AA mutant | 385 (± 74) | 9.1 (± 1.4) | 108.7 (± 3.5) | 55 (± 3.1) | 400 (± 32) | 14.3 (± 2) | 200 (± 40) | 91 (± 8.3) |
| Cam mutant | 213 (± 9.1) | 0.006 (± 0.001) | 0.03 (± 0.003) | 4.6 (± 0.6) | 208 (± 17) | 0.01 (± 0.002) | 0.05 (± 0.006) | 8.9 (± 2.5) |
| AA-cam mutant | 435 (± 38) | 2.6 (± 0.51) | 23.3 (± 5.9) | 8.8 (± 2.2) | 526 (± 83) | 5.3 (± 1.4) | 76.9 (± 5.9) | 24.4 (± 1.8) |
Binding isotherms for adrenergic ligands in competition for monoiodinated 125I-pindolol were generated as described inMaterials and Methods in membranes prepared from CHO cells expressing the indicated mutant or wild-type receptors. Data were analyzed with the computer program ALLFIT (DeLean et al, 1978) and are presented as dissociation constants. Mean ± S.E. computed from three to seven independent experiments.