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Updated: Jun 28, 2026
08:57
Myosin-Specific Adaptations of In vitro Fluorescence Microscopy-Based Motility Assays
Published on: February 4, 2021
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Research reviews on myosin head interactions with F-actin.
Yoon Ho Park1, Gang San Song1, Hyun Suk Jung2
1Department of Biochemistry, College of Natural Sciences, Kangwon National University, Chuncheon, 24341, Republic of Korea.
Applied Microscopy
|August 28, 2024
Summary
Myosin II
Area of Science:
- Muscle physiology
- Molecular biology
- Biophysics
Background:
- The sliding filament theory and cross-bridge model are foundational to muscle contraction.
- The native myosin molecule has two heads, but the cross-bridge model typically focuses on single-head interactions.
Purpose of the Study:
- To explore the possibility and mechanism of two-headed binding in myosin II to actin.
- To review recent evidence and identify future research directions for understanding this binding mode.
Main Methods:
- Review of recent studies utilizing electron tomography and resonance energy transfer.
- Discussion of potential high-resolution structural techniques like sub-tomogram averaging and single-particle analysis.
Main Results:
- Recent studies provide evidence supporting two-headed binding in myosin II.
- Regulatory light chain (RLC) flexibility is implicated as a key factor in enabling two-headed binding.
Conclusions:
- Two-headed binding in myosin II is supported by emerging evidence, with RLC flexibility playing a crucial role.
- Further high-resolution structural studies and investigations into binding predominance are needed for a comprehensive cross-bridge cycle model.
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Actin is a highly conserved cytoskeletal protein found abundantly in eukaryotic cells. It constitutes 10% weight of the total cellular protein in muscle cells, while in non-muscle cells, it is lower and makes up around 1–5 percent of the total cell protein. Actin found in the unicellular amoebae and complex multicellular animals is around 80% similar, demonstrating their conservation over a billion years of evolution. Actin coding genes are conserved within species and across different species.
01:14Generation of Straight or Branched Actin Filaments
The straight or branched structure formation of actin filaments is controlled by nucleating proteins such as the formins and Arp2/3 complex. Formin-mediated assembly results in straight filaments, whereas Arp2/3 protein complex-mediated assembly results in branched actin filaments.
Arp2/3 Complex
Arp2/3 complex is a seven-subunit complex consisting of two proteins similar to actin- Arp2 and Arp3, and five other subunits that help keep Arp2 and Arp3 inactive. When required, the complex is...
Arp2/3 Complex
Arp2/3 complex is a seven-subunit complex consisting of two proteins similar to actin- Arp2 and Arp3, and five other subunits that help keep Arp2 and Arp3 inactive. When required, the complex is...
01:19Actin Filament Depolymerization
Actin filaments (F-actin) are composed of actin subunits. The dissociation of actin monomers can occur from either end of F-actin. The rate of dissociation is faster from the minus-end or the pointed end, where the actin subunits exist with a bound ADP, together known as ADP-actin. The depolymerization of F-actin is aided by proteins, including the actin-depolymerizing factor (ADF) and cofilin family of proteins, gelsolin, and glia maturation factor (GMF).
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In F-actin, the ADF/cofilin proteins...
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01:16Actin and Myosin in Muscle Contraction
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01:10The Role of Actin and Myosin in Non-muscle Cells
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