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Updated: Jun 1, 2026
08:57
Myosin-Specific Adaptations of In vitro Fluorescence Microscopy-Based Motility Assays
Published on: February 4, 2021
Principles of unconventional myosin function and targeting.
M Amanda Hartman1, Dina Finan, Sivaraj Sivaramakrishnan
1Department of Biochemistry, Stanford University, Stanford, California 94305, USA.
Annual Review of Cell and Developmental Biology
|June 7, 2011
Summary
Unconventional myosins are essential cellular motors. Understanding their in vivo functions requires identifying their cargoes and regulatory complexes for cellular and developmental insights.
Area of Science:
- Cell Biology
- Biochemistry
- Molecular Motors
Background:
- Unconventional myosins are a superfamily of actin-based motors.
- These motors are involved in various cellular processes.
- Recent research has advanced understanding of their biophysical properties and cellular functions.
Purpose of the Study:
- To outline major themes in unconventional myosin superfamily research.
- To focus on principles guiding in vivo motor function and cellular targeting.
- To identify commonalities and open questions across myosin research.
Main Methods:
- Review and synthesis of existing research on unconventional myosins.
- Focus on overarching principles rather than comprehensive individual motor descriptions.
- Use of specific examples to illustrate key themes.
Main Results:
- Identification of major themes in unconventional myosin research.
- Highlighting principles of in vivo motor function and cellular localization.
- Illustrating themes with specific examples from the superfamily.
Conclusions:
- Further understanding of myosin roles in vivo necessitates identifying cellular cargoes.
- Recognizing protein complexes regulating motor attachment is crucial.
- Appreciating myosin functions at cellular and developmental levels requires this integrated approach.
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01:15Overview 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.
01:18Role of Myosin in Cell Migration
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Myosin II is a hexamer comprising two heavy chains with globular heads and coiled-coil tails, two regulatory light chains, and two essential light chains. The ATPase sites on the myosin heads hydrolyze ATP, and the released phosphate generates the force for contraction. It is...
Myosin II is a hexamer comprising two heavy chains with globular heads and coiled-coil tails, two regulatory light chains, and two essential light chains. The ATPase sites on the myosin heads hydrolyze ATP, and the released phosphate generates the force for contraction. It is...
01:16Actin and Myosin in Muscle Contraction
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...
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Actin and myosin or actomyosin filaments also play a significant role in cells other than those involved in muscle contraction (which occurs within the sarcomere of muscle cells). The mechanism of non-muscle cell contractile bundles was first observed in Dictyostelium and Acanthamoeba. In non-muscle cells, two bundles are commonly found: stress fibers and actomyosin adherence belts. These contractile bundles are smaller and less organized than the ones found in muscle cells. They are held...
01:08The 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...
Each myosin...
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