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Brain myosin-V is a two-headed unconventional myosin with motor activity

R E Cheney1, M K O'Shea, J E Heuser

  • 1Department of Biology, Yale University, New Haven, Connecticut 06511.

Cell
|October 8, 1993
PubMed

Insights

Chicken myosin-V, a distinct motor protein, was purified and characterized. This research details its structure, actin binding, and movement capabilities, identifying it as a barbed-end-directed motor.

Area of Science:

  • Biochemistry
  • Cell Biology
  • Molecular Motors

Background:

  • Myosins are actin-based motor proteins crucial for cellular functions.
  • Myosin-V represents a distinct class, separate from Myosin-I and Myosin-II.
  • Understanding novel myosin classes is vital for cellular mechanics research.

Purpose of the Study:

  • To purify and characterize chicken Myosin-V.
  • To elucidate the structural and motor properties of Myosin-V.
  • To determine the functional role of Myosin-V in cellular processes.

Main Methods:

  • Protein purification techniques.
  • Electron microscopy for structural visualization.
  • Biochemical assays to measure ATPase activity and actin binding.
  • In vitro motility assays to determine filament movement rates.

Main Results:

  • Chicken Myosin-V purified, revealing a two-headed structure with a ~30 nm stalk and a globular tail.
  • Myosin-V binds to and decorates F-actin, exhibiting actin-activated Mg-ATPase activity.
  • Demonstrated as a barbed-end-directed motor, moving actin filaments at speeds up to 400 nm/s.
  • Myosin-V does not form filaments and associates with calmodulin light chains.

Conclusions:

  • Chicken Myosin-V is a novel motor protein with unique structural and functional characteristics.
  • It functions as a barbed-end-directed motor, contributing to cellular transport mechanisms.
  • Further research into Myosin-V's cargo-binding and cellular roles is warranted.

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