Characterization of βARs stably expressed in HEK 293 cells
| Cell Line | EC50 for Epinephrine | Receptor Density | EpinephrineKd | Coupling Efficiency ± S.E.M. |
|---|---|---|---|---|
| nM | fmol/mg | nM | ||
| HA-βAR-6HIS | 8.2 ± 1.24, n = 6 | 2119 ± 254, n = 6 | 548 ± 133, n = 4 | 0.031 ± 0.009 |
| PKA− | 15.3 ± 3.66, n = 6 | 1501 ± 154, n = 6 | 503 ± 46, n = 3 | 0.021 ± 0.003 |
| S355,356,364A | 15.5 ± 0.79, n = 4 | 2887 ± 353, n = 4 | 579 ± 59, n = 3 | 0.012 ± 0.0012-150 |
| S355,356A | 10.8 ± 2.23, n = 6 | 1680 ± 154, n = 6 | 546 ± 160, n = 2 | 0.029 ± 0.017 |
| S356,364A | 16.8 ± 2.32, n = 6 | 1663 ± 207, n = 6 | 593 ± 62, n = 2 | 0.021 ± 0.003 |
| S356A | 50.1 ± 12.31, n = 3 | 691 ± 60, n = 3 | 463 ± 139, n = 3 | 0.012 ± 0.004 |
| S364A | 11.6 ± 0.73, n = 3 | 2281 ± 92, n = 3 | 426 ± 55, n = 2 | 0.016 ± 0.002 |
Membranes were prepared from naı̈ve HEK 293 cells expressing the HA-βAR-6HIS or mutant βARs. The membranes were assayed as described under Materials and Methods for epinephrineK d, receptor density, and for epinephrine-stimulated adenylyl cyclase activity to determine the EC50 value. Eq. 1, given under Materials and Methods, was used to calculate the coupling efficiency. The mean ± S.E.M. is given. None of the coupling efficiency values were significantly different, except for S355,356,364A.
↵2-150 Significantly different from PKA−,P < .05.