UMMS Affiliation

Division of Cell Biology and Imaging, Department of Radiology; Craig Lab

Publication Date


Document Type



Amino Acids, Peptides, and Proteins | Biophysics | Cell Biology | Cellular and Molecular Physiology | Molecular Biology | Structural Biology


Myosin and actin filaments are highly organized within muscle sarcomeres. Myosin-binding protein C (MyBP-C) is a flexible, rod-like protein located within the C-zone of the sarcomere. The C-terminal domain of MyBP-C is tethered to the myosin filament backbone, and the N-terminal domains are postulated to interact with actin and/or the myosin head to modulate filament sliding. To define where the N-terminal domains of MyBP-C are localized in the sarcomere of active and relaxed mouse myocardium, the relative positions of the N terminus of MyBP-C and actin were imaged in fixed muscle samples using super-resolution fluorescence microscopy. The resolution of the imaging was enhanced by particle averaging. The images demonstrate that the position of the N terminus of MyBP-C is biased toward the actin filaments in both active and relaxed muscle preparations. Comparison of the experimental images with images generated in silico, accounting for known binding partner interactions, suggests that the N-terminal domains of MyBP-C may bind to actin and possibly the myosin head but only when the myosin head is in the proximity of an actin filament. These physiologically relevant images help define the molecular mechanism by which the N-terminal domains of MyBP-C may search for, and capture, molecular binding partners to tune cardiac contractility.


Biophysics, Contraction and Cell Motility, Molecular Physiology, Myofilament, Protein Structure and Dynamics

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© 2021 Rahmanseresht et al. 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 After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 4.0 International license, as described at

DOI of Published Version



Rahmanseresht S, Lee KH, O'Leary TS, McNamara JW, Sadayappan S, Robbins J, Warshaw DM, Craig R, Previs MJ. The N terminus of myosin-binding protein C extends toward actin filaments in intact cardiac muscle. J Gen Physiol. 2021 Mar 1;153(3):e202012726. doi: 10.1085/jgp.202012726. PMID: 33528507; PMCID: PMC7852460. Link to article on publisher's site

Journal/Book/Conference Title

The Journal of general physiology

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Creative Commons License

Creative Commons Attribution-Noncommercial 4.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 4.0 License.