Table 2.
Rates of association of CKIIp with Ca2+-CaM in the absence of PEP-19 or Ng
| Ca2+ (μM) | Tyrosine fluorescence |
Inter-FRET |
Intra-FRET |
|||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Free CaM |
CaM + CKIIp |
CaMD + CKIIpA |
CaMD/A + CKIIp |
|||||||||
| Rate (s−1) | Amp | Rate 1 (s−1) | Amp 1 | Rate 2 (s−1) | Amp 2 | Rate 1 (s−1) | Amp 1 | Rate 2 (s−1) | Amp 2 | Rate (s−1) | Amp | |
| 0.26 | nd | 1.5 ± 0.1 | 50 | 0.45 ± 0.01 | 49 | 13 ± 0.2 | 66 | 2.4 ± 0.1 | 26 | 1.2 ± 0.2 | 87 | |
| 0.50 | 8.2 ± 0.5 | 9 | 5.0 ± 0.2 | 45 | 1.51 ± 0.03 | 56 | 26 ± 0.3 | 76 | 4.0 ± 0.1 | 20 | 3.2 ± 0.3 | 95 |
| 1.10 | 11.4 ± 0.3 | 27 | 12.9 ± 0.4 | 50 | 4.75 ± 0.21 | 50 | 68 ± 0.5 | 80 | 8.2 ± 0.2 | 20 | 10.1 ± 0.5 | 100 |
| 2.19 | 17.8 ± 0.3 | 56 | 22.7 ± 0.8 | 93 | 163 ± 2.6 | 86 | 15.9 ± 0.4 | 14 | 30.2 ± 2.3 | 95 | ||
| 3.26 | 30.7 ± 0.5 | 68 | 43.2 ± 0.8 | 93 | 278 ± 2.5 | 85 | 27.2 ± 1.0 | 14 | 49.2 ± 2.5 | 86 | ||
| 4.56 | 46.5 ± 0.7 | 84 | 69.9 ± 0.7 | 87 | 377 ± 2.2 | 74 | 36.1 ± 1.2 | 16 | 73.1 ± 2.2 | 74 | ||
At least five stopped-flow traces were averaged and fitted using Applied Photophysics SX-Pro Data. The rates are shown with the estimated error of the fit.
To allow comparisons of amplitudes obtained from biphasic fits, as well as fits for different levels of Ca2+F, the amplitudes are expressed relative to the overall amplitude at the Ca2+F that gave the largest overall change in fluorescence within the data set. In the absence of CKIIp, the largest change in fluorescence was at 5 mM Ca2+.