Key result
Muscle β-connectin aggregated both myosin and actin filaments at low ionic strengths and appreciably enhanced the Mg2+-activated ATPase activity of actomyosin.
Connectin interacts with and aggregates myosin and actin filaments at low ionic strengths, enhancing actomyosin ATPase activity, which may relate to its localization and function in myofibrils.
Connectin may organize sarcomeres in cardiac muscle; leaves open functional roles in vivo.
The interaction of the muscle elastic protein connectin with myosin and actin filaments was investigated by turbidimetry, viscosity, flow birefringence measurements, and electron microscopic observations. In KCl concentrations lower than 0.15 M at pH 7.0 at 25 degrees C, both myosin and actin filaments were aggregated by connectin. Myosin filaments were entangled with each other in the presence of connectin. Actin filaments were assembled into bundles under the influence of connectin just as under that of alpha-actinin. The physiological significance of the interactions of connectin with myosin and actin filaments is discussed in relation to the localization of connectin in myofibrils. The Mg2+-activated ATPase activity of actomyosin was appreciably enhanced by connectin in the presence of KCl concentrations lower than 0.1 M. The extent of activation by connectin was smaller than by alpha-actinin. The enhancement of the ATPase activity may be due to acceleration of the onset of superprecipitation of actomyosin.
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Kimura et al. (1984) studied this question. Muscle β-connectin was evaluated on Interaction with myosin and actin filaments and Mg2+-activated ATPase activity of actomyosin. Muscle β-connectin aggregated both myosin and actin filaments at low ionic strengths and appreciably enhanced the Mg2+-activated ATPase activity of actomyosin.
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