125I-CYP | Ligands (Ki) | |||||
---|---|---|---|---|---|---|
Kd | Bmax | Formoterol | Procaterol | Salmeterol4-c | Isoproterenol | |
pM | pmol/mg | nM | ||||
WT β2AR | 26.5 ± 7.0 | 2.1 ± 0.2 | 35 ± 8 | 240 ± 26 | 7.4 ± 3.3 | 190 ± 26 |
E306A- | 40.4 ± 8.4 | 0.2 ± 0.04 | 28 ± 8 | 140 ± 8 | ||
V307A- | 24.0 ± 2.0 | 2.6 ± 0.4 | 42 ± 0.3 | 230 ± 34 | ||
Y308A- | 23.0 ± 2.0 | 5.5 ± 0.7 | 740 ± 170b | 2800 ± 340b | 184 ± 60b 4-c | 1300 ± 130b 4-c |
I309A- | 27.1 ± 4.5 | 4.2 ± 0.7 | 120 ± 28 | 340 ± 82 | ||
L310A- | 26.9 ± 2.1 | 3.2 ± 0.2 | 26 ± 3 | 150 ± 26 | ||
L311A- | 19.9 ± 3.2 | 3.6 ± 0.2 | 39 ± 4 | 500 ± 120 | ||
I314A- | 23.7 ± 2.6 | 2.5 ± 0.3 | 23 ± 8 | 150 ± 26 | ||
V317A- | 23.4 ± 6.1 | 3.1 ± 0.8 | 43 ± 1 | 220 ± 19 | ||
G320A- | 33.0 ± 11.3 | 7.4 ± 1.4 | 46 ± 5 | 300 ± 23 | ||
L324A- | 30.1 ± 11.3 | 3.5 ± 0.9 | 98 ± 10 | 840 ± 614-a | ||
Y308F- | 16.5 ± 1.3 | 4.4 ± 0.2 | 96 ± 17 | 1400 ± 300b | 32 ± 3 | 370 ± 98 |
The binding of ligands to the WT β2AR and alanine-substituted β2AR mutants were determined by competition with 50pM125I-CYP. The data were analyzed using the nonlinear least-squares regression computer program as described underExperimental Procedures. The results are shown as the mean ± S.E. from three to four separate experiments.