(A) pCa-tension plots comparing native fibers (▲, N=10), and fibers reconstituted with BVC actin (●, N=12) and WT actin (■, N=11). TLC was subtracted from tension and normalized against Tact; (B) pCa-tension plots comparing fibers reconstituted with A331P actin (○, N=13) and WT actin (■, N=11). In (A) and (B), symbols represent the mean ± SE, and continuous curves are the results of fitting the averaged data to Eq. 1 of Ref. [28]. Tension was normalized against T0 (initial tension of native fibers before thin-filament extraction). (C) Results of Ca2+ sensitivity (pCa50), and (D) cooperativity (nH) are compared for native fibers, BVC actin reconstituted fibers, WT actin reconstituted fibers, and A331P actin reconstituted fibers. The value of the pCa50 and nH were calculated by averaging the fitted parameters of each curve. *Significantly different from WT actin reconstituted fibers (p<0.05).