Key result
Electron microscopy reveals striated muscle myosin filaments comprise 12 close-packed subunits.
Why the study?
The detailed subunit organization of the myosin filament in chicken striated muscle was not directly observed and confirmed at the molecular level.
Answers are grounded in this paper and cite their sources.
Supports myosin filament model in avian muscle; confirms theoretical consensus but leaves open relevance to human cardiac sarcomeres.
The subunit organization of the myosin filament of chicken striated muscle has been observed directly in cross-sections in electron microscopy. The organization consists of three centrally located and nine peripherally located subunits in a close-packed arrangement. This arrangement is that predicted by a previously derived model for the detailed molecular organization of the myosin filament (Pepe, 1966 a, 1967 a, 1971). Each subunit measures approximately 30 A in diameter and the center-to-center distance is approximately 37 A. If these measurements are considered to be on the high side, then they indicate that each subunit represents one myosin molecule. However, it is not possible to determine unequivocally whether one or two myosin molecules per subunit are present on the basis of this work.
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Pepe et al. (1972) studied Normal striated muscle structure. Electron microscopy and Markham rotation was evaluated on Subunit organization of the myosin filament. Electron microscopy of chicken striated muscle revealed that the myosin filament consists of three centrally located and nine peripherally located subunits in a close-packed arrangement.
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