Table 3. Summary of cAMP assay pEC50 values for ECD alanine mutants of either CT(a) or RAMP1 at the predicted interface between these proteins in the CT(a) and AMY1(a) (CT(a) /RAMP1) receptors when stimulated with hCT, rAmy (rat amylin) or hαCGRP.
|
hCT |
rAmy |
|||||
|---|---|---|---|---|---|---|
| Mutant | pEC50 WT | pEC50 mutant | Fold Shift | pEC50 WT | pEC50 mutant | Fold Shift |
| Q52A CT(a) | 9.48±0.21 (5) | 9.33±0.23 (5) | — | 8.02±0.20 (5) | 8.17±0.09 (5) | — |
| Y53A CT(a) | 9.63±0.29 (5) | 9.52±0.11 (5) | — | 8.00±0.07 (4) | 8.06±0.11 (4) | — |
| Y56A CT(a) | 10.02±0.19 (4) | 10.05±0.12 (4) | — | 8.68±0.15 (5) | 8.66±0.13 (5) | — |
|
hαCGRP |
rAmy |
|||||
| Q52A AMY1(a) | 9.62±0.17 (4) | 8.95±0.13 (4)* | 5 | 9.66±0.12 (4) | 9.07±0.09 (4)** | 4 |
| Y53A AMY1(a) | 9.49±0.18 (4) | 7.90±0.11 (4)*** | 39 | 9.52±0.22 (5) | 8.25±0.20 (5)** | 19 |
| Y56A AMY1(a) | 9.71±0.22 (6) | 7.97±0.21 (6)*** | 55 | 9.78±0.18 (6) | 8.47±0.17 (6)*** | 20 |
| Y66A RAMP1 | 9.91±0.17 (4) | 8.20±0.18 (4)*** | 51 | 9.67±0.21(4) | 8.88 ±0.03 (4)** | 6 |
| H97A RAMP1 | 9.86±0.18 (4) | 8.82±0.14 (4)** | 11 | 9.67±0.21 (4) | 9.00±0.14 (4)* | 5 |
| F101A RAMP1 | 9.82±0.11 (4) | 8.49±0.15 (4)*** | 21 | 9.67±0.21 (4) | 8.89±0.10 (4)* | 6 |
Data are mean±s.e.m. Number of independent experiments indicated in parentheses. *P<0.05;**P<0.01; ***P<0.001 versus WT by unpaired t-test.