Abstract
The dependences of thin filament sliding velocity on the calcium concentration in solution (pCa 5 to 8) for rabbit cardiac myosin isoforms V1 and V3 were determined in a set of experiments using an in vitro motility assay with a reconstructed thin filament. The constructed pCa-versus-velocity curves had a sigmoid shape. It was demonstrated that the sliding velocity of regulated thin filament at the saturating calcium concentration (pCa 5) did not differ from the actin sliding velocity for each isoform. The determined values of Hill’s cooperativity coefficient for isomyosins V1 and V3 were 1.04 and 0.75, respectively. It was demonstrated that isomyosin V3 was more sensitive to calcium as compared with isomyosin V1. Using the same assay, the dependence of thin filament sliding velocity on the concentration of the actin-binding protein α-actinin (analog of a force-velocity dependence) was determined at the saturating calcium concentration for each myosin isoform (V1 and V3). The results suggest that the calcium regulation of V1 and V3 contractile activity follows different mechanisms.
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Abbreviations
- BSA:
-
bovine serum albumin
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Original Russian Text © L.V. Nikitina, G.V. Kopylova, D.V. Shchepkin, L.B. Katsnel’son, 2008, published in Biofizika, 2008, Vol. 53, No. 6, pp. 956–961.
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Nikitina, L.V., Kopylova, G.V., Shchepkin, D.V. et al. Assessment of the mechanical activity of cardiac isomyosins V1 and V3 by the in vitro motility assay with regulated thin filament. BIOPHYSICS 53, 510–514 (2008). https://doi.org/10.1134/S0006350908060079
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DOI: https://doi.org/10.1134/S0006350908060079