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Updated: Jun 28, 2026
08:49
Self-Assembly of Microtubule Tactoids
Published on: June 23, 2022
Microtubule-driven multimerization recruits ase1p onto overlapping microtubules
Lukas C Kapitein1, Marcel E Janson, Siet M J L van den Wildenberg
1Department of Physics and Astronomy, VU University Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands.
Current Biology : CB
|November 4, 2008
Summary
Ase1p protein localization to overlapping microtubules is driven by concentration-dependent multimerization. This mechanism allows cells to precisely build microtubule networks, like the mitotic spindle, essential for cell division.
Area of Science:
- Cell Biology
- Molecular Biology
- Biophysics
Background:
- Microtubule (MT) crosslinking proteins, such as ase1p/PRC1/Map65, are crucial for constructing cellular MT networks, including the mitotic spindle.
- These proteins exhibit specific localization to antiparallel overlapping MTs, suggesting a mechanism for spatial signaling.
Purpose of the Study:
- To elucidate the mechanism underlying the specific localization of ase1p, a fission yeast homolog of the ase1p/PRC1/Map65 family.
- To investigate the role of protein multimerization in the targeted localization of ase1p to microtubules.
Main Methods:
- In vitro experiments using purified ase1-GFP to observe diffusion and multimerization on single and overlapping microtubules.
- In vivo studies using live fission yeast cells to track ase1-GFP behavior on MTs.
- Analysis of ase1p truncations to identify domains responsible for MT binding and multimerization.
Main Results:
- Ase1-GFP dimers diffuse on single MTs and multimerize above a concentration threshold.
- This multimerization threshold is significantly lower on overlapping MTs compared to single MTs.
- Ase1-GFP diffusion and multimerization were observed in vivo, supporting a biologically relevant mechanism.
Conclusions:
- Ase1p localization is driven by a cooperative multimerization mechanism that is sensitive to MT geometry and local protein concentration.
- This finely tuned mechanism allows cells to precisely target proteins to specific MT arrangements, essential for building functional MT networks.
- The findings reveal a novel strategy for spatial organization within the cell, utilizing protein self-assembly on microtubules.
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