TABLE 1.
Pharmacological characteristics of Rlu-tagged secretin receptor constructs expressed in intact COS-1 cells
Shown are the IC50 values of secretin binding to COS-1 cells expressing each of the noted secretin receptor constructs. Shown also are EC50 values for secretin-stimulated intracellular cAMP responses in these cells, as well as Emax values reflecting maximal cAMP concentrations achieved. Values are expressed as means ± S.E.M. of data from at least three independent experiments. All the YFP-tagged constructs behaved similarly to the complementary Rlu-tagged constructs.
| Rlu-Tagged Receptors | IC50 | EC50 | Emax |
|---|---|---|---|
| nM | pmol/106 cells | ||
| WT | 3.9 ± 0.5 | 0.31 ± 0.05 | 198 ± 46 |
| Q235C | 7.6 ± 0.6 | 0.51 ± 0.11 | 185 ± 50 |
| G236C | 3.3 ± 1.0 | 0.49 ± 0.10 | 201 ± 44 |
| A239C | 4.9 ± 0.5 | 0.64 ± 0.14 | 187 ± 49 |
| F240C | 3.2 ± 0.6 | 0.72 ± 0.15 | 188 ± 38 |
| G241C | Not detected | N.D. | N.D. |
| W242C | Not detected | N.D. | N.D. |
| G243C | 5.0 ± 0.6 | 0.39 ± 0.13 | 195 ± 43 |
| S244C | 4.2 ± 0.9 | 0.25 ± 0.04 | 190 ± 33 |
| P245C | Not detected | N.D. | N.D. |
| A246C | 4.6 ± 0.1 | 0.39 ± 0.09 | 193 ± 35 |
| I247C | 5.0 ± 0.6 | 0.36 ± 0.08 | 188 ± 40 |
| F248C | 3.0 ± 0.3 | 0.41 ± 0.08 | 196 ± 46 |
| V249C | 4.3 ± 1.1 | 0.76 ± 0.19 | 200 ± 52 |
| A250C | 5.0 ± 1.6 | 0.65 ± 0.12 | 197 ± 47 |
N.D., not determined.