Figure 5.

Rate of force redevelopment (k_tr) was enhanced by mutant S2 proteins that were permeabilized in fibers^PKA.A, raw k_tr traces for nontransgenic (NTg) fibers treated with all four S2 proteins with a concentration range from 9 to 45 μM, which determined that the 9 μM concentration of S2 proteins was sufficient to differentiate the effect of hS2^Wt to all mutant hS2 proteins. B, raw k_tr traces and C, values for fibers^control that were untreated (black) and treated with 9 μM hS2^Wt (green), hS2^R870H (blue), hS2^E924K (orange), and hS2^E930Δ (red) proteins. D, raw k_tr traces and E, values for fibers^PKA that were untreated (black) and treated with 9 μM hS2^Wt (green), hS2^R870H (blue), hS2^E924K (orange), and hS2^E930Δ (red) proteins. F, k_tr traces and G, values for fibers^{λ-phosphatase} that were untreated (black) and treated with 9 μM hS2^Wt (green), hS2^R870H (blue), hS2^E924K (orange), and hS2^E930Δ (red) proteins. Statistical analyses were performed by one-way ANOVA with Tukey’s multiple comparison test with single pooled variance. n = 5 fibers/3 mice (12 weeks old, FVB/N, mixed sex) were used at submaximal pCa 5.7 and sarcomere length 2.0 μM in the study. Data are expressed as the mean ± SEM. See Table 4 for analysis of main factors and interactions. ∗∗p < 0.01, and ∗∗∗p < 0.001 versus untreated control. hS2^E924K, human recombinant proximal S2 protein with E924K mutation; hS2^E930Δ, human recombinant proximal S2 protein with E930Δ mutation; hS2^R870H, human recombinant proximal S2 protein with R870H mutation; hS2^Wt, human recombinant proximal S2 WT protein; S2, subfragment 2 region.