Jove
Visualize
Contact Us
JoVE
x logofacebook logolinkedin logoyoutube logo
ABOUT JoVE
OverviewLeadershipBlogJoVE Help Center
AUTHORS
Publishing ProcessEditorial BoardScope & PoliciesPeer ReviewFAQSubmit
LIBRARIANS
TestimonialsSubscriptionsAccessResourcesLibrary Advisory BoardFAQ
RESEARCH
JoVE JournalMethods CollectionsJoVE Encyclopedia of ExperimentsArchive
EDUCATION
JoVE CoreJoVE BusinessJoVE Science EducationJoVE Lab ManualFaculty Resource CenterFaculty Site
Terms & Conditions of Use
Privacy Policy
Policies

Related Concept Videos

Overview of Myosin Structure and Function01:15

Overview of Myosin Structure and Function

6.9K
Myosins are a family of molecular motor proteins, first identified in the skeletal muscles, where they are responsible for muscle contraction. Along with their role in muscle contraction, these proteins also play a role in the intracellular transport of molecules and vesicles. There are twenty-four classes of myosins based on their domain sequence and organization. Of the twenty-four, six classes (Myosin I, Myosin II, Myosin V, Myosin VI, Myosin VII, and Myosin X)  have been well...
6.9K
Actin and Myosin in Muscle Contraction01:16

Actin and Myosin in Muscle Contraction

25.3K
Actin and myosin are contractile proteins that form the sarcomere found in skeletal muscle tissues for regulating muscle contraction. Actin, a globular contractile protein, interacts with myosin for muscle contraction. The skeletal tissue appears striped or striated under a microscope due to the repeated arrangement of contractile proteins actin and myosin along the length of myofibrils. Dark A bands and light I bands repeat along myofibrils, and the alignment of myofibrils in the cell causes...
25.3K
Excitation-Contraction Coupling in Skeletal Muscles01:20

Excitation-Contraction Coupling in Skeletal Muscles

16.0K
Excitation-contraction coupling is a series of events that occur between generating an action potential and initiating a muscle contraction. It occurs at the triad, a structure found in skeletal muscle fibers that comprise a T-tubule and terminal cisternae of the sarcoplasmic reticulum on each side. These triads are visible in longitudinally sectioned muscle fibers. They are typically located at the A-I junction — the junction between the A and I bands of the sarcomere.
When an action...
16.0K
The Sarcomere01:08

The Sarcomere

17.1K
A sarcomere is a microscopic segment repeating in a myofibril. The sarcomere fundamentally consists of two main myofilaments: thick filaments called myosin and thin filaments called actin. These filaments interact by sliding past each other in response to stimulus. In addition to myosin and actin, several other proteins, such as tropomyosin, troponin, titin, nebulin, myomesin, α-actinin, and dystrophin, play crucial roles in regulating, structuring, and functioning of the sarcomere.
Each...
17.1K
Generation of Straight or Branched Actin Filaments01:14

Generation of Straight or Branched Actin Filaments

3.9K
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...
3.9K
Cross-bridge Cycle01:26

Cross-bridge Cycle

123.3K
As muscle contracts, the overlap between the thin and thick filaments increases, decreasing the length of the sarcomere—the contractile unit of the muscle—using energy in the form of ATP. At the molecular level, this is a cyclic, multistep process that involves binding and hydrolysis of ATP, and movement of actin by myosin.
123.3K

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by
Same author

Humans and rhesus macaques share maturation pathways of HIV-1 envelope-reactive V3-glycan bnAb lineages.

Science translational medicine·2026
Same author

Enhanced B cell priming induces broadly neutralizing HIV-1 apex antibodies.

Nature·2026
Same author

Mechanistic and antigenic boundaries of Henipavirus and Parahenipavirus glycoproteins.

Nature communications·2026
Same author

Priming of Multiple HIV Neutralizing B Cell Precursors in Humans.

medRxiv : the preprint server for health sciences·2026
Same author

Safety and immunogenicity of an HIV envelope trimer immunogen that elicits CD4 binding site neutralizing antibody precursors (HVTN 300).

medRxiv : the preprint server for health sciences·2026
Same author

Recurrent SARS-CoV-2 Omicron broadly neutralizing humanized antibodies in different single human V<sub>H</sub>1-2-rearranging mouse models.

Proceedings of the National Academy of Sciences of the United States of America·2026

Related Experiment Video

Updated: Feb 22, 2026

Probing Myosin Ensemble Mechanics in Actin Filament Bundles Using Optical Tweezers
06:53

Probing Myosin Ensemble Mechanics in Actin Filament Bundles Using Optical Tweezers

Published on: May 4, 2022

2.7K

Coupling between myosin head conformation and the thick filament backbone structure.

Zhongjun Hu1, Dianne W Taylor1, Robert J Edwards2

  • 1Florida State University, Institute of Molecular Biophysics, Tallahassee, FL 32306-4380, USA.

Journal of Structural Biology
|October 2, 2017
PubMed
Summary

New research reveals how myosin head arrangement in insect flight muscle thick filaments changes with tension. This finding offers a novel hypothesis for stretch activation and shortening deactivation in striated muscles.

Keywords:
Cryoelectron microscopyImage reconstructionMuscle physiologyStriated muscle

More Related Videos

Tuning the Contractility and Deformation Modes of Active Actin-Based Assemblies In Vitro: From Two-Dimensional Active Networks to Liquid Crystal Drops
06:48

Tuning the Contractility and Deformation Modes of Active Actin-Based Assemblies In Vitro: From Two-Dimensional Active Networks to Liquid Crystal Drops

Published on: July 11, 2025

953
Myosin-Specific Adaptations of In vitro Fluorescence Microscopy-Based Motility Assays
08:57

Myosin-Specific Adaptations of In vitro Fluorescence Microscopy-Based Motility Assays

Published on: February 4, 2021

6.7K

Related Experiment Videos

Last Updated: Feb 22, 2026

Probing Myosin Ensemble Mechanics in Actin Filament Bundles Using Optical Tweezers
06:53

Probing Myosin Ensemble Mechanics in Actin Filament Bundles Using Optical Tweezers

Published on: May 4, 2022

2.7K
Tuning the Contractility and Deformation Modes of Active Actin-Based Assemblies In Vitro: From Two-Dimensional Active Networks to Liquid Crystal Drops
06:48

Tuning the Contractility and Deformation Modes of Active Actin-Based Assemblies In Vitro: From Two-Dimensional Active Networks to Liquid Crystal Drops

Published on: July 11, 2025

953
Myosin-Specific Adaptations of In vitro Fluorescence Microscopy-Based Motility Assays
08:57

Myosin-Specific Adaptations of In vitro Fluorescence Microscopy-Based Motility Assays

Published on: February 4, 2021

6.7K

Area of Science:

  • Muscle physiology
  • Structural biology
  • Biophysics

Background:

  • Asynchronous flight muscle relies on stretch activation for function, a phenomenon also seen in cardiac muscle.
  • The thick filament is a critical site for muscle tension regulation due to its role in bearing motor-generated and external forces.
  • Previous understanding of stretch activation lacked detailed structural insights into the thick filament's regulatory mechanisms.

Purpose of the Study:

  • To investigate the structural basis of myosin head arrangement within the interacting heads motif of insect flight muscle thick filaments.
  • To elucidate the relationship between thick filament backbone structure and myosin head positioning.
  • To propose a mechanism for stretch activation and shortening deactivation based on structural findings.

Main Methods:

  • High-resolution structural analysis of the thick filament from Lethocerus asynchronous flight muscle.
  • Examination of the impact of changes in helical angle on the ordering of myosin heads within the interacting heads motif.

Main Results:

  • First structural evidence linking myosin head arrangement in the interacting heads motif to the thick filament backbone structure.
  • A specific helical angle change (0.16°) was found to disorder the blocked myosin head preferentially.
  • This structural disordering suggests a tension-dependent mechanism influencing myosin head dynamics.

Conclusions:

  • The study proposes a novel hypothesis for stretch activation and shortening deactivation in striated muscles.
  • Tension-induced changes in thick filament structure likely regulate myosin head binding to the thin filament.
  • The blocked head may preferentially bind the thin filament under force, followed by the free head, explaining force production dynamics.