Related Experiment Video
Updated: Jul 29, 2025
08:57
Myosin-Specific Adaptations of In vitro Fluorescence Microscopy-Based Motility Assays
Published on: February 4, 2021
6.0K
Nonmuscle myosin 2 filaments are processive in cells
Eric A Vitriol1, Melissa A Quintanilla2, Joseph J Tidei2
1Department of Neuroscience and Regenerative Medicine, Augusta University, Augusta, Georgia.
Biophysical Journal
|May 23, 2023
Summary
Nonmuscle myosin 2 (NM2) exhibits processive movement within cells, challenging previous assumptions. This cellular property, observed in various cell types, broadens the known functions of this ubiquitous motor protein.
Area of Science:
- Cell Biology
- Molecular Motors
- Cytoskeletal Dynamics
Background:
- Directed cellular transport relies on processive cytoskeletal motors.
- Myosin 2 motors are typically associated with contractility, not processivity, due to actin filament interactions.
Purpose of the Study:
- To establish nonmuscle myosin 2 (NM2) processivity as a cellular property.
- To characterize NM2 processive movement in vivo and compare it with in vitro data.
Main Methods:
- Live-cell imaging of NM2 in CAD cells and fibroblasts.
- Analysis of NM2 movement against actin dynamics in cellular protrusions.
- Comparison of NM2A and NM2B isoform processivity.
Main Results:
- NM2 filaments exhibit processive movement in vivo, particularly on bundled actin in cell protrusions.
- In vivo processive velocities align with in vitro measurements.
- NM2A demonstrates slightly faster processivity than NM2B, and this property is observed in both neuronal and non-neuronal cells.
Conclusions:
- Nonmuscle myosin 2 (NM2) possesses cellular processivity, expanding its functional repertoire.
- NM2's processive motility contributes to cellular dynamics beyond contraction.
- These findings highlight NM2's broader role in cellular organization and transport.
Related Concept Videos
01:15Overview of Myosin Structure and Function
4.5K
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...
4.5K
01:10The Role of Actin and Myosin in Non-muscle Cells
3.6K
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...
3.6K
01:18Role of Myosin in Cell Migration
2.3K
Myosins are multimeric motor proteins involved in various cellular processes such as migration, adhesion, and proliferation. Myosin II is the most common type in animal cells, which binds and cross-links actin filaments.
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....
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....
2.3K
01:16Actin and Myosin in Muscle Contraction
13.5K
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...
13.5K
01:43The Movement of Organelles and Vesicles
4.6K
In eukaryotic cells, cytoskeletal filaments such as actin, microtubules, and intermediate filaments form a mesh-like cytoskeletal network. These filaments serve as tracks for transporting cellular cargo. Specialized motor proteins use the chemical energy stored in adenosine triphosphate (ATP) for this transport. During interphase, microtubules are polarized, with the plus-end towards the cell periphery and the minus-end towards the cell center. Two microtubule-associated motor proteins,...
4.6K
01:08The Sarcomere
8.3K
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...
Each...
8.3K