TABLE 2.
Thin filament TnC Ca2+ binding characteristics
Binding characteristics of Ca2+ to TnC in thin filaments reconstituted with human cTn containing wild type (Tn WT), Ser-150-pseudo-phosphorylated cTnI (Tn S150D), Ser-23/24-pseudophosphorylated cTnI (Tn S23D/S24D), or combined Ser-23/24- and Ser-150-pseudophosphorylated cTnI (Tn S23D/S24D/S150D). Values are the mean ± S.E. EC50, the Ca2+ concentration in μm at 50% maximal binding; Hill, slope of the binding-Ca2+ plot; n, number of fibers in each group.
| Thin filament Tn | EC50 | Hill | n |
|---|---|---|---|
| Tn WT | 2.52 ± 0.10a (P,PP) | 2.49 ± 0.08a (PP,PPP) | 10 |
| Tn S150D | 1.03 ± 0.16a (W,PP,PPP) | 1.07 ± 0.03a (PP,PPP) | 9 |
| Tn S23D/S24D | 8.33 ± 0.60a (W,P,PPP) | 8.39 ± 0.10a (W,P) | 5 |
| Tn S23D/S24D/S150D | 3.69 ± 0.80a (P,PP) | 3.47 ± 0.13a (W,P) | 4 |
a ANOVA Bonferroni p < 0.05; W, significantly different vs. Tn WT; P, significantly different vs. Tn S150D; PP, significantly different vs. Tn S23D/S24D; PPP, significantly different vs. S23D/S24D/S150D.