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Updated: Jul 19, 2025
08:57
Myosin-Specific Adaptations of In vitro Fluorescence Microscopy-Based Motility Assays
Published on: February 4, 2021
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Endocytic myosin-1 is a force-insensitive, power-generating motor
Ross T A Pedersen1, Aaron Snoberger2, Serapion Pyrpassopoulos2
1Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA.
The Journal of Cell Biology
|August 7, 2023
Summary
Myosin type I (Myo5) in yeast endocytosis is activated by phosphorylation. Its force-insensitive kinetics suggest it augments actin forces during cell entry.
Area of Science:
- Cell biology
- Biophysics
- Molecular motor function
Background:
- Myosins are crucial for clathrin-mediated endocytosis, but their specific roles remain unclear due to limited biophysical data.
- Myosins exhibit varied mechanochemical properties, influencing their function in cellular processes.
Purpose of the Study:
- To investigate the in vitro force-dependent kinetics of Saccharomyces cerevisiae endocytic type I myosin (Myo5).
- To elucidate the molecular contribution of Myo5 to clathrin-mediated endocytosis.
Main Methods:
- In vitro analysis of Myo5's force-dependent kinetics.
- Characterization of Myo5's mechanochemical activity and response to phosphorylation.
Main Results:
- Myo5 functions as a low-duty-ratio motor, with its activity increasing approximately 10-fold upon phosphorylation.
- The motor's working stroke and actin-detachment kinetics are largely insensitive to force.
- Myo5's in vitro mechanochemistry resembles cardiac myosin more than slow anchoring myosins.
Conclusions:
- Myo5's properties suggest it generates power to enhance actin assembly-based forces during endocytosis.
- Phosphorylation significantly modulates Myo5's motor activity, highlighting its regulatory mechanism.
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