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. 2013 Oct;142(4):413–423. doi: 10.1085/jgp.201310971

Figure 5.

Figure 5.

Effect of RcTnT1–43Δ and RcTnT44–73Δ on pCa50 in the presence of α- or β-MHC isoform. Normalized tension values were plotted against a range of pCa to derive the pCa–tension relationships. (A) pCa–tension relationships in fibers containing α-MHC. (B) pCa–tension relationships in fibers containing β-MHC. Arrows in B indicate that a shift to β-MHC counteracts the desensitizing effect of RcTnT1–43Δ on myofilament Ca2+ sensitivity. Note that the curve for RcTnT1–43Δ is shifted to the right in A, but the rightward shift is attenuated in B (see arrows). The Hill equation was fitted to the pCa–tension relationships to estimate pCa50. (C) Estimates of pCa50 in fibers containing α-MHC. (D) Estimates of pCa50 in fibers containing β-MHC. RcTnT1–43Δ decreased pCa50 significantly in α-MHC fibers, an effect that was counteracted in β-MHC fibers. Number of determinations was at least seven for each group. Values are reported as mean ± SEM. ***, P < 0.001.