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Direct interaction between a myosin V motor and the Rab GTPases Ypt31/32 is required for polarized secretion

Zhanna Lipatova1, Andrei A Tokarev, Yui Jin

  • 1Laboratory for Molecular Biology, Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL 60607, USA.

Molecular Biology of the Cell
|July 26, 2008
PubMed

Insights

The Ypt31/32 GTPase directly binds Myo2, a myosin V motor, to ensure polarized secretion in yeast. This interaction is crucial for trans-Golgi vesicle transport and cell growth.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Rab GTPases are known regulators of endocytic vesicle motility.
  • The role of Ypt/Rab GTPases in exocytic compartment motility remains largely unexplored.
  • In yeast, Ypt31/32 are essential for trans-Golgi vesicle formation.

Purpose of the Study:

  • To investigate the role of Ypt31/32 in the motility of exocytic compartments.
  • To identify the direct interaction between Ypt31/32 and the myosin V motor Myo2.
  • To elucidate the mechanism by which Ypt31/32 regulate polarized secretion.

Main Methods:

  • Yeast-two hybrid system to screen for interacting proteins.
  • Coprecipitation assays with recombinant proteins to confirm direct interaction.
  • Microscopy (colocalization, intracellular localization) to assess protein function in vivo.
  • Genetic interaction analysis and functional complementation assays.

Main Results:

  • Ypt31/32 directly interact with the globular-tail domain of Myo2 in a GTP-dependent manner.
  • Genetic and functional data confirm Myo2 as a physiological effector of Ypt31/32.
  • Mutations disrupting the Ypt31/32-Myo2 interaction lead to defective Myo2 localization and unpolarized secretion.
  • Ypt31/32 are involved in both vesicle formation and Myo2-dependent motility.

Conclusions:

  • Ypt31/32 GTPases regulate the polarized transport of trans-Golgi vesicles by directly recruiting the Myo2 myosin V motor.
  • This study reveals a novel function for Ypt/Rab GTPases in controlling the motility of exocytic compartments.
  • The Ypt31/32-Myo2 pathway is essential for polarized secretion and cell growth in yeast.

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