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Related Concept Videos

Overview of Myosin Structure and Function01:15

Overview of Myosin Structure and Function

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 characterized.
Myasthenia Gravis ll: Pathophysiology01:22

Myasthenia Gravis ll: Pathophysiology

The disease process of myasthenia gravis begins at the neuromuscular junction, where antibodies attack key proteins needed for muscle activation. This immune reaction weakens signal transmission, leading to the characteristic muscle fatigue and weakness that define the condition.Immune-Mediated DamageIn most individuals, antibodies target acetylcholine receptors (AChRs) on the postsynaptic membrane of muscle cells. By blocking acetylcholine binding, these antibodies prevent the nerve signal...
The Sarcomere01:08

The Sarcomere

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 myosin...
Alterations in Muscle Tone lll01:11

Alterations in Muscle Tone lll

Rigidity and myotonia are distinct abnormalities of muscle tone that affect resistance and relaxation during movement. Although both involve altered muscle contraction, they arise from different neurological and muscular mechanisms.CharacteristicsRigidity is characterized by uniform resistance to passive movement across the entire range, independent of speed, affecting flexors and extensors equally. It may appear as lead-pipe rigidity (smooth, constant resistance) or cogwheel rigidity...
Myocarditis I: Introduction01:21

Myocarditis I: Introduction

Myocarditis is inflammation of the myocardium, which is the muscular layer of the heart.EtiologyMyocarditis has a diverse etiology, including a wide range of infectious and non-infectious causes:Infectious CausesViral: Common viruses include Coxsackie A and B, adenovirus, parvovirus B19, enteroviruses, and influenza A.Bacterial: Examples include infections caused by Streptococcus, Staphylococcus, and Mycoplasma species.Rickettsial: Infections like Rocky Mountain spotted fever can result in...
Covalently Linked Protein Regulators02:04

Covalently Linked Protein Regulators

Proteins can undergo many types of post-translational modifications, often in response to changes in their environment. These modifications play an important role in the function and stability of these proteins. Covalently linked molecules include functional groups, such as methyl, acetyl, and phosphate groups, and also small proteins, such as ubiquitin. There are around 200 different types of covalent regulators that have been identified.
These groups modify specific amino acids in a protein.

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Related Experiment Video

Updated: Jun 20, 2026

Isolation and Differentiation of Primary Myoblasts from Mouse Skeletal Muscle Explants
06:53

Isolation and Differentiation of Primary Myoblasts from Mouse Skeletal Muscle Explants

Published on: October 15, 2019

Myosin Post-Translational Modifications Associated With Critical Illness Myopathy.

Fernando Ribeiro1,2, Bruno Di Geronimo3, Nicola Cacciani1,4

  • 1Center for Molecular Medicine (CMM), Karolinska Institutet, Stockholm, Sweden.

Acta Physiologica (Oxford, England)
|June 19, 2026
PubMed
Summary
This summary is machine-generated.

Critical illness myopathy causes severe muscle weakness in ICU patients. Abnormal myosin modifications, not just muscle loss, lead to non-force-generating muscle fibers and profound weakness.

Keywords:
critical careliquid chromatography–tandem mass spectrometrymechanical ventilationmuscle contractionskeletal muscle

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Last Updated: Jun 20, 2026

Isolation and Differentiation of Primary Myoblasts from Mouse Skeletal Muscle Explants
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Published on: October 15, 2019

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

Area of Science:

  • Biochemistry
  • Molecular Biology
  • Intensive Care Medicine

Background:

  • Critical illness myopathy (CIM) is a severe complication of intensive care, causing significant muscle mass and function loss in patients.
  • Functional deficits in CIM often disproportionately exceed muscle mass and myosin loss, with unclear underlying mechanisms.
  • The emergence of myosin-expressing, non-force-generating muscle fibers in CIM remains poorly understood.

Purpose of the Study:

  • To investigate the mechanisms of myosin dysfunction in intensive care unit (ICU) patients with critical illness myopathy.
  • To identify molecular alterations in myosin contributing to force loss and the development of non-force-generating muscle fibers.

Main Methods:

  • Proteomic analysis using mass spectrometry was performed on single muscle fibers from six ICU patients.
  • Patients underwent a 12-day period of mechanical ventilation and immobilization.
  • Molecular dynamics simulations were employed to model the impact of myosin modifications on its function.

Main Results:

  • Muscle fibers showed decreased size and specific force after 12 days of mechanical ventilation and immobilization.
  • A subset of myosin-expressing fibers (9-21%) lost contractile function, becoming non-force generating.
  • Twenty-seven post-translational myosin modifications, including oxidation, were identified and linked to decreased specific force; oxidation caused myosin head rigidity.

Conclusions:

  • Abnormal myosin post-translational modifications, beyond muscle wasting and myosin loss, significantly contribute to muscle weakness in CIM.
  • These modifications, particularly oxidation, impair myosin function and lead to the development of non-force-generating muscle fibers.
  • Understanding these molecular mechanisms is crucial for developing targeted therapies for critical illness myopathy.