Muscle Contraction Mechanism Based on Actin Filament Rotation
Muscle contraction is caused by relative sliding movement between interdigitating actin and myosin filaments. It has been thought that myosin heads protruding from the myosin filament rotate between two orientations, while they repeat detachment from and attachment to actin filament coupled to the ATP hydrolysis cycle and the rotation of the head may cause the sliding. Recently atomic structure obtained from X-ray crystallography supports the rotation of the myosin head relative to the actin filament. A small conformational change in the ATP binding domain is transmitted to a neck domain that connects a motor domain (head) and tail domain, depending on the chemical state of nucleotide bound. Thus the neck domain acts as a lever-arm that can cause a displacement of 5–10 nm for the muscle myosin. This lever-arm swinging model has been a paradigm not only for the muscle myosin but also for unconventional myosins. Large stepsize of unconventional processive myosin V motor can be explained by its large lever arm within the frame of the lever-arm swinging model.
KeywordsScanning Probe Myosin Head Actin Monomer Myosin Molecule Myosin Versus
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- Wakabayashi, K., Ueno, Y., Takezawa, Y., and Sugimoto, Y., 2001. Muscle contraction mechanism: Use of X-ray synchrotron radiation. Nature Encyclopedia of life science pp. 1–11.Google Scholar