Table I.

Summary of Ligand Binding Properties of Wild-Type β₂-AR and V114 Mutant Receptors^a

Receptor	Kd (nM)	95% confidence intervals	Bmax (pmol/mg)
Wild-type	3.0	2.35–3.74	18 ± 0.6
V114I	4.1	3.73–4.51	24 ± 0.4
V114C	7.8	5.51–10.22	30 ± 1.7
V114L	15.5	11.53–19.49	36 ± 2.5
V114Eb	35.8	20.31–51.42	31 ± 4.2

^aThe values are expressed as the mean ± S.E (n = 3–5 experiments), and the experiment is performed using [3H] dihydroalprenolol as the radioligand (TRK 649, GE Health care). No significant specific binding detected for the V114G, V114T, V114S, V114D, and V114W mutants under the assay conditions.

^bHigh nonspecific binding (15–20% of total binding).