Key result
Mutations D137L and G126R in tropomyosin increased the maximal sliding velocity of regulated actin filaments and the Ca2+-sensitivity of actin-myosin interaction in vitro.
Mutations D137L and G126R in tropomyosin alter the Ca2+-sensitivity and sliding velocity of actin-myosin interactions, likely by influencing interactions between the central part of Tm and the myosin head.
In vitro motility changes merit validation in cardiomyopathy models; leaves open relevance to human disease phenotypes.
We show that the mutations D137L and G126R, which stabilize the central part of the tropomyosin (Tm) molecule, increase both the maximal sliding velocity of the regulated actin filaments in the in vitro motility assay at high Са(2+) concentrations and the Са(2+)-sensitivity of the actin-myosin interaction underlying this sliding. Based on an analysis of the recently published data on the structure of the actin-Tm-myosin complex, we suppose that the physiological effects of these mutations in Tm can be accounted for by their influence on the interactions between the central part of Tm and certain sites of the myosin head.
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Shchepkin et al. (2013) studied this question. Mutations D137L and G126R in tropomyosin was evaluated on Maximal sliding velocity and Ca2+-sensitivity of actin-myosin interaction. Mutations D137L and G126R in tropomyosin increased the maximal sliding velocity of regulated actin filaments and the Ca2+-sensitivity of actin-myosin interaction in vitro.
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