Related Experiment Video
Updated: Jul 19, 2026
10:01
Production of Xenopus tropicalis Egg Extracts to Identify Microtubule-associated RNAs
Published on: June 27, 2013
Regulation of Op18 during spindle assembly in Xenopus egg extracts
P P Budde1, A Kumagai, W G Dunphy
1Department of Molecular & Cell Biology, University of California, Berkeley, 94720, USA.
The Journal of Cell Biology
|April 4, 2001
Summary
Oncoprotein 18 (Op18) regulates microtubule dynamics. The polo-like kinase Plx1 promotes spindle assembly by inhibiting Op18 phosphorylation, stabilizing microtubules.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Oncoprotein 18 (Op18) is a key microtubule-destabilizing protein.
- Op18 activity is regulated by phosphorylation.
- Understanding Op18 regulation is crucial for cell division.
Purpose of the Study:
- To investigate the role of Op18 phosphorylation sites in Xenopus spindle assembly.
- To identify chromatin-associated regulators of Op18.
- To elucidate the mechanism by which Plx1 affects Op18 and spindle formation.
Main Methods:
- Site-directed mutagenesis of Op18 (Op18-AAA, Op18-EEE).
- Xenopus egg extract assays to monitor spindle assembly.
- Affinity chromatography to assess protein binding.
- Chromatin pulldown assays and kinase identification.
- Plx1 depletion experiments.
Main Results:
- Op18 phosphorylation site mutations differentially affected microtubule stability.
- Op18's microtubule-destabilizing activity correlated with tubulin binding.
- Xenopus polo-like kinase 1 (Plx1) was identified as a chromatin-associated kinase regulating Op18 phosphorylation.
- Plx1 depletion inhibited Op18 hyperphosphorylation and spindle assembly.
Conclusions:
- Plx1 plays a critical role in regulating Op18 phosphorylation.
- Plx1 promotes microtubule stabilization and spindle assembly by inhibiting Op18.
- This study identifies a novel regulatory pathway for microtubule dynamics during cell division.
Related Concept Videos
02:50Spindle Assembly
Spindle assembly occurs through three, often coexisting, pathways – the centrosome-mediated pathway, the chromatin-mediated pathway, and the microtubule-mediated pathway – collectively contributing to form a robust spindle apparatus.
In most cells, centrosomes are the primary microtubule nucleation centers. In the centrosome-mediated pathway, the G2-prophase transition triggers centrosome maturation and increased microtubule nucleation. Progressive nucleation results in a microtubule array...
In most cells, centrosomes are the primary microtubule nucleation centers. In the centrosome-mediated pathway, the G2-prophase transition triggers centrosome maturation and increased microtubule nucleation. Progressive nucleation results in a microtubule array...
02:19The Spindle Assembly Checkpoint
The spindle assembly checkpoint is a molecular surveillance mechanism ensuring the fidelity of chromosome segregation during anaphase. The checkpoint monitors the completion of all the prerequisite steps before chromosome segregation to determine whether the segregation process should proceed or be delayed.
Many proteins function together to control the spindle assembly checkpoint. Mutations affecting these proteins may allow cells to proceed into anaphase prematurely, resulting in the...
Many proteins function together to control the spindle assembly checkpoint. Mutations affecting these proteins may allow cells to proceed into anaphase prematurely, resulting in the...
02:02Meiosis II
Meiosis II entails cell division and segregation of the sister chromatids, resulting in the production of four unique haploid gametes. The steps for meiosis II are similar to mitosis, except that meiosis II occurs in haploid cells, whereas mitosis occurs in diploid cells.
The timing and cell division patterns of meiosis differ between males and females. In male meiosis, the centrosomes are part of the formation of the meiotic spindle. However, in oocytes, including that of humans, Drosophila,...
The timing and cell division patterns of meiosis differ between males and females. In male meiosis, the centrosomes are part of the formation of the meiotic spindle. However, in oocytes, including that of humans, Drosophila,...