Fig. 4.

Phosphatase and PKA treatment of cTnC-exchanged fibers. Force–pCa relations were measured before extraction of endogenous mcTnC (dashed lines, open triangle) and after reconstitution with hcTnC^L29Q (a) or hcTnC^WT (b) and treatment with PP1c (solid lines, open circle). After phosphatase treatment, the pCa₅₀ values were not significantly different between fibers reconstituted with hcTnC^L29Q or hcTnC^WT, respectively. Symbols represent mean ±SEM for n = 5 preparations. After phosphatase treatment, PKA was added (dotted lines, open square), resulting in significant rightward shifts of the force–pCa relations of similar magnitude. Symbols represent mean ±SEM for n = 3 preparations