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. 2014 May;85(5):811–829. doi: 10.1124/mol.114.091587

TABLE 2.

Log EC50 values and % maximum response to isoprenaline for CRE-SPAP production for the agonists cimaterol and CGP12177 at the human β1-WT and chimeric β1/β2-adrenoceptors

Mutations in the β1-WT mean that each TM region in turn is mutated to that of the β2-WT (see Table 1). Log KB values for several antagonists for inhibition of the cimaterol and CGP12177 responses were determined. These data were obtained from stable cell lines, and n in the table refers to the number of separate experiments. The table shows that the most consistent and highly significant difference between the β1-WT receptor and all of the TM-swap mutants is that obtained from β1-TM4 when CGP12177 is the agonist. As CGP12177 agonist responses occur at the secondary low-affinity conformation of the β1-WT receptor, this suggests that the β1-TM4 receptor mutations alter this conformation in some way.

Cimaterol Log EC50 % Isoprenaline n Log KB CGP20712A n Log KB Bisoprolol n Log KB ICI118551 n Log KB Propranolol n Log KB Carvedilol n Log KB CGP12177 n
Cimaterol as agonist: β1 stable cell lines
 β1-WT −8.25 ± 0.14 95.8 ± 2.9 8 −9.18 ± 0.07 4 −8.48 ± 0.17 5 −6.96 ± 0.04 5 −8.52 ± 0.08 12 −9.89 ± 0.13 5 −9.55 ± 0.12 8
 β1-TM1 −7.91 ± 0.05* 96.5 ± 3.3 11 −9.35 ± 0.10 9 −8.65 ± 0.12 5 −6.96 ± 0.05 9 −8.66 ± 0.07 16 −9.88 ± 0.08 5 −9.77 ± 0.07 15
 β1-TM2 −8.19 ± 0.03 98.9 ± 3.0 15 −8.78 ± 0.12 8 −8.15 ± 0.07 7 −7.47 ± 0.03* 14 −8.52 ± 0.03 24 −9.53 ± 0.18 8 −9.90 ± 0.09 17
 β1-TM3 −8.82 ± 0.03* 102.4 ± 2.5 9 −9.34 ± 0.12 9 −8.43 ± 0.07 4 −7.31 ± 0.04* 10 −8.53 ± 0.06 15 −9.92 ± 0.16 5 −9.49 ± 0.06 13
 β1-TM4 −8.15 ± 0.02 99.2 ± 1.8 10 −9.50 ± 0.13 11 −8.81 ± 0.04 5 −8.07 ± 0.06* 9 −8.99 ± 0.04* 15 −9.81 ± 0.12 6 −9.63 ± 0.08 17
 β1-TM5 −8.48 ± 0.05 103.0 ± 1.7 9 −9.09 ± 0.04 11 −7.91 ± 0.03 5 −7.01 ± 0.06 11 −8.71 ± 0.04 17 −9.96 ± 0.09 6 −9.68 ± 0.09 17
 β1-TM6 −8.59 ± 0.03* 103.2 ± 2.2 10 −8.52 ± 0.07 8 −8.10 ± 0.15 5 −7.92 ± 0.05* 12 −8.90 ± 0.05* 18 −10.13 ± 0.09 6 −9.58 ± 0.06 14
 β1-TM7 −8.54 ± 0.05 106.1 ± 2.5 10 −8.45 ± 0.08 7 −8.19 ± 0.06 5 −7.80 ± 0.05* 12 −8.95 ± 0.05* 18 −10.06 ± 0.03 3 −9.39 ± 0.05 13
CGP12177 Log EC50 % Isoprenaline n Log KB CGP20712A n Log KB Bisoprolol n Log KB ICI118551 n Log KB Propranolol n Log KB Carvedilol n
CGP12177 as agonist: β1 stable cell lines
 β1-WT −8.18 ± 0.08 73.8 ± 5.6 10 −7.16 ± 0.06 14 −5.83 ± 0.14 4 −5.90 ± 0.15 9 −6.18 ± 0.06 13 −7.25 ± 0.18 7
 β1-TM1 −7.83 ± 0.05 53.7 ± 3.9 10 −7.41 ± 0.13 11 −5.77 ± 0.18 4 −5.79 ± 0.09 3 −6.55 ± 0.12 13 −7.72 ± 0.13 7
 β1-TM2 −8.27 ± 0.09 53.5 ± 3.9 14 −7.13 ± 0.08 13 −6.72 ± 0.18 7 −5.87 ± 0.05 6 −6.87 ± 0.15* 18 −8.52 ± 0.15*,** 7
 β1-TM3 −8.07 ± 0.03 70.5 ± 3.6 9 −7.45 ± 0.05 12 −5.83 ± 0.13 4 −5.83 ± 0.09 7 −6.31 ± 0.05 16 −7.45 ± 0.09 6
 β1-TM4 −9.27 ± 0.06*,** 29.2 ± 1.4*,** 10 −9.49 ± 0.08*,** 9 −8.83 ± 0.21*,** 7 −7.93 ± 0.11*,** 11 −8.85 ± 0.09*,** 15 −9.73 ± 0.21*,** 7
 β1-TM5 −7.91 ± 0.03 60.1 ± 3.4 10 −6.68 ± 0.04* 11 −5.31 ± 0.13 5 −5.71 ± 0.15 8 −6.23 ± 0.09 15 −7.53 ± 0.16 7
 β1-TM6 −7.83 ± 0.02* 63.5 ± 2.8 11 −5.97 ± 0.08*,** 12 −5.22 ± 0.14 3 −5.79 ± 0.04 11 −6.05 ± 0.06 19 −7.24 ± 0.18 7
 β1-TM7 −7.08 ± 0.02*,** 68.5 ± 3.8 11 −6.86 ± 0.05 10 −5.67 ± 0.05 5 −6.67 ± 0.03*,** 13 −6.42 ± 0.06 16 −7.35 ± 0.12 6
*

P < 0.001; one-way ANOVA with post hoc Newman–Keuls comparing values from the mutant receptors with those obtained from the β1-WT. Thus, the log EC50 for CGP12177 at β1-TM4 is different from that obtained from the β1-WT with P < 0.001; **P < 0.001; one-way ANOVA with post hoc Newman–Keuls comparing each value with all other values in this set. Thus, the log EC50 value for CGP12177 at β1-TM4 is different from those obtained for β1-WT, β1-TM1, β1-TM2, β1-TM3, β1-TM5, β1-TM6, and β1-TM7, with P < 0.001 in all cases.