Lattice arrangement of myosin filaments correlates with fiber type in rat skeletal muscle
- Department of Biological Sciences, Illinois Institute of Technology, Chicago, IL
- Division of Cell Biology and Imaging, Department of Radiology, University of Massachusetts Medical School, Worcester, MA
The thick (myosin-containing) filaments of vertebrate skeletal muscle are arranged in a hexagonal lattice, interleaved with an array of thin (actin-containing) filaments with which they interact to produce contraction. X-ray diffraction and EM have shown that there are two types of thick filament lattice. In the simple lattice, all filaments have the same orientation about their long axis, while in the superlattice, nearest neighbors have rotations differing by 0° or 60°. Tetrapods (amphibians, reptiles, birds, and mammals) typically have only a superlattice, while the simple lattice is confined to fish. We have performed x-ray diffraction and electron microscopy of the soleus (SOL) and extensor digitorum longus (EDL) muscles of the rat and found that while the EDL has a superlattice as expected, the SOL has a simple lattice. The EDL and SOL of the rat are unusual in being essentially pure fast and slow muscles, respectively. The mixed fiber content of most tetrapod muscles and/or lattice disorder may explain why the simple lattice has not been apparent in these vertebrates before. Furthermore, this is supported by only weak simple lattice diffraction in the x-ray pattern of mouse SOL, which has a greater mix of fiber types than rat SOL. We conclude that the simple lattice might be common in tetrapods. The correlation between fiber type and filament lattice arrangement suggests that the lattice arrangement may contribute to the functional properties of a muscle.
- Research Organization:
- Argonne National Laboratory (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
- Sponsoring Organization:
- USDOE Office of Science (SC); National Institutes of Health (NIH)
- Grant/Contract Number:
- AC02-06CH11357; AR072036; AR067279; HL139883; S10OD018090-01
- OSTI ID:
- 1573437
- Alternate ID(s):
- OSTI ID: 1578236
- Journal Information:
- Journal of General Physiology, Journal Name: Journal of General Physiology Vol. 151 Journal Issue: 12; ISSN 0022-1295
- Country of Publication:
- United States
- Language:
- English
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