TABLE 1.
Inactivation and dissociation rates of the Ca2+/αCaM·phospho-Thr286-CaMKII complex
The autoinactivation processes of the Ca2+/CaM·phospho-Thr286-αCaMKII complex were dissected by measurements of Ca2+ and CaM dissociation, inactivation, and Thr305 autophosphorylation rates.
| Temperature |
k |
||||||
|---|---|---|---|---|---|---|---|
| Ca2+ offa | CaM “stretching” | CaM dissociation (polarization) (slow phase) | Inhibition (EGTA) | Thr305 autophosphorylation (EGTA) | Inhibition (Ca2+) | Thr305 autophosphorylation (Ca2+) | |
| s−1 | |||||||
| 21 °C | 8 ± 1.4 | 0.00105 ± 0.00047 (n = 4)c | 0.0013 ± 0.0002 | 0.000450 ± 0.000002d(n = 2)c | 0.0013 ± 0.0002 | ||
| 0.31 ± 0.03 | 0.82 ± 0.02(0.70)b | ||||||
| 0.023 ± 0.016 | 0.088 ± 0.002(0.30)b | ||||||
| 30 °C | 0.00485 ± 0.00064(n = 2)c | 0.0086 ± 0.0002 | 0.0043 ± 0.0028(n = 3)c | 0.0060 ± 0.0051(n = 2)c | |||
| 37 °C | 0.0200 ± 0.0075e(n = 5)c | 0.01255 ± 0.00007(n = 2)c | 0.0098 ± 0.0064 | 0.01335 ± 0.00092(n = 2)c | 0.0157 ± 0.0050 | ||
a Data from Tzortzopoulos et al. (19).
b Relative amplitude.
c n specifies the number of independent experiments; the mean and the S.D. are shown. Where n = 1, the fitted value and the S.E. of the fit is given.
d The temperature in this experiment was 22 °C.
e A p value of 0.244 obtained using an unpaired two-tailed t test showed this value not to be significantly different from the rate constant of 0.01255 ± 0.000071 (S.D.) s−1 (n = 2) obtained for inhibition induced by EGTA.