| Cyclic nucleotide assay . | Kd (µM) . | SEM . |
|---|---|---|
| Direct binding assay | ||
| fcAMP | 0.6 | 0.1 |
| fcGMP | 2.7 | 0.5 |
| Competition assay | ||
| cAMP | 36 | 12 |
| cGMP | 28 | 9 |
| Activation of SthK by cAMP | EC50 (µM) | SEM |
| Bilayer recordings | 17 | 0.8 |
| Stopped flow | 107 | 8 |
| Inhibition of SthK by cGMP | Ki (µM) | SEM |
| Bilayer recordings | 4 | 0.5 |
| Stopped flow | 6 | 0.7 |
| Cyclic nucleotide assay . | Kd (µM) . | SEM . |
|---|---|---|
| Direct binding assay | ||
| fcAMP | 0.6 | 0.1 |
| fcGMP | 2.7 | 0.5 |
| Competition assay | ||
| cAMP | 36 | 12 |
| cGMP | 28 | 9 |
| Activation of SthK by cAMP | EC50 (µM) | SEM |
| Bilayer recordings | 17 | 0.8 |
| Stopped flow | 107 | 8 |
| Inhibition of SthK by cGMP | Ki (µM) | SEM |
| Bilayer recordings | 4 | 0.5 |
| Stopped flow | 6 | 0.7 |
Table 1 provides the numerical values obtained from the binding and activation studies of SthK. Ki values for cGMP inhibition were calculated according to Eq. 12. The listed values are correlated with the data shown in Figs. 2, 3, 4, and 5 and represent means ± SEM for at least three independent measurements.