UMMS Affiliation
Division of Cell Biology and Imaging, Department of Radiology; Craig Lab
Publication Date
2021-12-10
Document Type
Article
Disciplines
Amino Acids, Peptides, and Proteins | Cell Biology | Cellular and Molecular Physiology | Enzymes and Coenzymes
Abstract
Super-relaxation is a state of muscle thick filaments in which ATP turnover by myosin is much slower than that of myosin II in solution. This inhibited state, in equilibrium with a faster (relaxed) state, is ubiquitous and thought to be fundamental to muscle function, acting as a mechanism for switching off energy-consuming myosin motors when they are not being used. The structural basis of super-relaxation is usually taken to be a motif formed by myosin in which the two heads interact with each other and with the proximal tail forming an interacting-heads motif, which switches the heads off. However, recent studies show that even isolated myosin heads can exhibit this slow rate. Here, we review the role of head interactions in creating the super-relaxed state and show how increased numbers of interactions in thick filaments underlie the high levels of super-relaxation found in intact muscle. We suggest how a third, even more inhibited, state of myosin (a hyper-relaxed state) seen in certain species results from additional interactions involving the heads. We speculate on the relationship between animal lifestyle and level of super-relaxation in different species and on the mechanism of formation of the super-relaxed state. We also review how super-relaxed thick filaments are activated and how the super-relaxed state is modulated in healthy and diseased muscles.
Keywords
Contraction, Cell Motility
Rights and Permissions
© 2021 Craig and Padrón. This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.rupress.org/terms/). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 4.0 International license, as described at https://creativecommons.org/licenses/by-nc-sa/4.0/).
DOI of Published Version
10.1085/jgp.202113012
Source
Craig R, Padrón R. Structural basis of the super- and hyper-relaxed states of myosin II. J Gen Physiol. 2022 Jan 3;154(1):e202113012. doi: 10.1085/jgp.202113012. Epub 2021 Dec 10. PMID: 34889960; PMCID: PMC8669498. Link to article on publisher's site
Journal/Book/Conference Title
The Journal of general physiology
Related Resources
PubMed ID
34889960
Repository Citation
Craig RW, Padron R. (2021). Structural basis of the super- and hyper-relaxed states of myosin II. Radiology Publications. https://doi.org/10.1085/jgp.202113012. Retrieved from https://escholarship.umassmed.edu/radiology_pubs/669
Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 4.0 License.
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Amino Acids, Peptides, and Proteins Commons, Cell Biology Commons, Cellular and Molecular Physiology Commons, Enzymes and Coenzymes Commons