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Centriolar CPAP/SAS-4 Imparts Slow Processive Microtubule Growth
Ashwani Sharma1, Amol Aher2, Nicola J Dynes3
1Laboratory of Biomolecular Research, Department of Biology and Chemistry, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland.
Developmental Cell
|May 25, 2016
Summary
The human centriolar protein CPAP caps microtubule plus ends, slowing their growth. This molecular lid ensures slow assembly of centriolar microtubules, controlling organelle length.
Area of Science:
- Cell Biology
- Molecular Biology
- Biophysics
Background:
- Centrioles are essential microtubule-based organelles with slow assembly rates.
- The mechanism behind the slow growth of centriolar microtubules remains unclear.
- Several proteins interact with tubulin, but their role in regulating centriolar microtubule dynamics is unknown.
Purpose of the Study:
- To elucidate the mechanism by which centriolar proteins regulate microtubule growth.
- To investigate the role of the human centriolar protein CPAP in microtubule dynamics.
- To understand how CPAP contributes to centriolar length control.
Main Methods:
- Crystallography
- Biophysical assays
- Reconstitution assays
- Cellular experiments
Main Results:
- CPAP binds and caps microtubule plus ends at a specific β-tubulin interaction site.
- CPAP activity significantly dampens microtubule growth and enhances microtubule stability by inhibiting catastrophes and promoting rescues.
- CPAP's capping function is crucial for limiting centriolar microtubule growth in cells.
Conclusions:
- CPAP acts as a molecular lid, regulating microtubule dynamics at the plus end.
- This capping activity ensures the slow assembly of centriolar microtubules.
- CPAP is essential for controlling centriolar length and maintaining organelle homeostasis.
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