TABLE 2

K_D and log K_D values from [³H]CGP 12177 whole cell binding experiments in the stable mixed populations of each construct.

The K_D values for [³H]CGP 12177 were calculated from the saturation experiments. The log K_D values for the other ligands were calculated from the IC₅₀ values obtained from competition experiments and converted to K_D values as outlined in the methods. There was no specific binding to any of the Asp138 or Asn363 mutants. There was also no specific binding seen when D138A and N363A were cotransfected. Values are mean ± S.E.M. from separate experiments. The total number of stable populations of the mutant is shown in Table 1.

Mutation	K_D [³H]CGP 12177	n	Log K_D CGP 20712A	n	Log K_D propranolol	n	Log K_D isoprenaline	n	Log K_D cimaterol	n
Wildtype β1	0.31 ± 0.04 nM	11	−8.97 ± 0.04	7	−7.94 ± 0.10	4	−6.09 ± 0.06	7	−6.31 ± 0.07	4
D104A	0.37 ± 0.03 nM	10	−8.36 ± 0.07	8	−7.99 ± 0.07	4	−5.75 ± 0.03	7	−6.09 ± 0.06	4
D104N	0.51 ± 0.03 nM	10	−8.54 ± 0.05	8	−8.06 ± 0.06	4	−5.86 ± 0.07	7	−6.20 ± 0.06	4
S228A	7.92 ± 0.33 nM	15	−9.17 ± 0.07	17	−9.42 ± 0.04	16	−5.00 ± 0.04	17	−6.95 ± 0.05	16
S229A	2.20 ± 0.28 nM	15	−9.36 ± 0.09	4	−7.89 ± 0.05	5	−5.16 ± 0.10	6	−5.97 ± 0.08	6
S232A	0.30 ± 0.03 nM	15	−9.44 ± 0.11	7	−8.16 ± 0.06	6	−5.11 ± 0.06	6	−6.01 ± 0.08	6
F341A	1.66 ± 0.09 nM	15	−7.89 ± 0.10	15	−7.97 ± 0.03	16	−6.05 ± 0.05	16	−6.14 ± 0.02	16
N344A	1.59 ± 0.17 nM	14	−8.87 ± 0.09	6	−8.94 ± 0.09	6	−5.32 ± 0.09	6	−5.92 ± 0.07	6