Table II.
Summary of Competition Ligand Binding of Wild-Type β2-AR and Mutant Receptorsa
| Ligands (Ki) μM (95% confidence intervals) |
||||
|---|---|---|---|---|
| Receptor | Norepinephrine | Epinephrine | Isoproterenol | Albuterol (salbutamol) |
| Wild-type | 84 (49–144) | 4.9 (3.5–7.0) | 4.2 (2.4–7.5) | 25 (21–30) |
| V114I | 167 (52–535) | 33 (16–68) | 6.6 (3.1–14) | 11 (4.1–31) |
| V114L | 2014 (722–5613) | 486 (241–978) | 92 (48–177) | 82 (42–160) |
| V114C | 960 (434–2123) | 312 (169–572) | 57 (35 to 93) | 101 (57–176) |
| V114Eb | 752 (164–3437) | 2725 (1277–5813) | 1400 (590–3320) | 2129 (954–4748) |
a
The binding of unlabelled agonists to wild-type β2-AR and mutant receptors was determined by competition with 3 nM [3H] dihydroalprenolol as the radioligand (TRK 649, GE Health care). Data obtained from determinations of three independent transfections and analyzed by nonlinear regression as described under Material and Methods section.
b
High nonspecific binding of 15–20% observed.