Ligand-binding properties of β2-AR alone versus α1D-/β2-AR
HEK-293 cells were either transfected with α1D-AR alone or cotransfected with α1D-AR and β2-AR. Specific binding of [125I]-pindolol was measured as described under Materials and Methods. Bmax and Kd values were calculated by nonlinear regression of saturation curves, and Ki values for inhibition of binding by unlabeled CGP-12177A, CGP-20712, and ICI 118,551 were determined. Each value represents the mean ± S.E.M. for three to four experiments performed in duplicate.
β2-AR | α1D-/β2-AR | |
|---|---|---|
| [125I]Pindolol (Kd) | 244 ± 51 pM | 359 ± 87 pM |
| [125I]Pindolol (Bmax) | 328 ± 40 fmol/mg | 358 ± 46 fmol/mg |
| (±)CGP-12177A (Ki) | 5.1 ± 1.4 nM | 8.7 ± 2.3 nM |
| CGP-20712 (Ki) | 15.7 ± 2.1 nM | 13.6 ± 3.6 nM |
| ICI 118,551 (Ki) | 3.5 ± 0.9 nM | 7.1 ± 2.9 nM |