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Characterization of myosin V binding to brain vesicles
1Department of Cell Biology, Duke University Medical Center, Durham, North Carolina 27710, USA.
The Journal of Biological Chemistry
|January 25, 2000
Summary
Polyphosphates solubilize vesicular myosin II and V by inducing conformational changes, disrupting their binding to vesicle receptors. This mechanism is crucial for generating and segregating subcellular compartments.
Area of Science:
- Cell Biology
- Molecular Motors
Background:
- Myosin II and V are essential for creating and separating subcellular compartments.
- Vesicular myosins play a critical role in intracellular transport and organelle dynamics.
Purpose of the Study:
- To investigate the interaction of myosins II and V with vesicles.
- To determine the mechanism by which polyphosphates affect vesicular myosin binding.
Main Methods:
- Density sedimentation, electron microscopy, and immunofluorescence were used to study myosin-vesicle association.
- Polyphosphate-induced solubilization assays were performed for myosins II and V.
- Scatchard analysis quantified myosin V binding to isolated vesicle components.
Main Results:
- Myosins II and V associate with a common subset of vesicles.
- Polyphosphates, particularly pyrophosphate and tripolyphosphate, effectively solubilize myosins II and V.
- Myosin V exhibits saturable binding to vesicle receptors with high affinity (K(m) = 10 nM), with over 100 myosin V molecules per vesicle.
Conclusions:
- Polyphosphate anions bind to myosins II and V, inducing conformational changes that disrupt their receptor binding.
- This polyphosphate-mediated mechanism is proposed to regulate the association and dissociation of myosins from vesicles, impacting compartment formation and segregation.