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Figure 3
Reconstruction of the 3D structure of myosin filament from an actually recorded diffraction pattern. (a) A diffraction pattern from actin-extracted bumblebee flight muscle fibers. The arrows indicate meridional reflections from myosin-head crowns. (b) The CAP calculated from the diffraction pattern in (a). The numbers indicate the levels of the 14.5 nm crowns of myosin heads. The arrows indicate the peaks on the z axis at the 1.5th, 3rd and 3.5th levels of myosin crowns. (c) The solved structure of the myosin filament. The black lines on the cylinder indicate the levels of crowns and the small arrows indicate the additional mass lying midway between two neighboring crowns. The green, red and blue double-headed arrows indicate the vertical vectors of 1.5, 3 and 3.5 × 14.5 nm lengths, respectively. (d) Superposition of the actually observed CAP and the idealized CAP calculated from the solved structure (blue dots). (e) Superposition of the interacting-heads motif (Sweeney, 2018BB20) and the three-mass unit on the solved structure. The size of the motif was adjusted by using the scale bar in the work of Alamo (2016BB2) (right). The values on the scale bar in (a) are d spacings (nm).

Volume 8| Part 4| July 2021| Pages 544-548
ISSN: 2052-2525