TABLE 2.
Binding properties of CT-secretin receptor chimeras and key CT receptor mutants by natural peptide ligands
Shown are the parameters of secretin or CT binding to COS-1 cells expressing each of the noted receptor constructs. All values are the means ± S.E. of data from three independent experiments performed in duplicate. CR, CT receptor; SR, secretin receptor.
| Construct |
Kd |
Bmax |
||
|---|---|---|---|---|
| Secretin | CT | Secretin | CT | |
| nm | binding sites/cell × 103 | |||
| CR | >1,000 | 1.1 ± 0.3 | 99 ± 25 | |
| SR | 3.3 ± 0.5 | >1,000 | 101 ± 31 | |
| Ce1S | >1,000 | >1,000 | ||
| Se1C | 270 ± 40 | >1,000 | 75 ± 19 | |
| Ce2S | 69 ± 21 | >1,000 | 87 ± 22 | |
| Se2C | >1,000 | 100 ± 27 | 78 ± 21 | |
| Ce1e2S | >1,000 | 288 ± 43 | 55 ± 18 | |
| Se1e2C | 160 ± 27 | >1,000 | 89 ± 29 | |
| Y150A-CR | 12 ± 3 | 123 ± 31 | ||
| L151A-CR | 6.6 ± 1.4 | 113 ± 28 | ||
| I153A-CR | 4.3 ± 1.1 | 72 ± 19 | ||