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Updated: May 26, 2026
12:26
Identification of Cyclin-dependent Kinase 1 Specific Phosphorylation Sites by an In Vitro Kinase Assay
Published on: May 3, 2018
Phosphorylation of Cdc5 regulates its accumulation
Kobi J Simpson-Lavy1, Michael Brandeis
1The Department of Genetics, The Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel. brandeis@cc.huji.ac.il.
Cell Division
|December 30, 2011
Summary
Phosphorylation of Cdc5 by Cdk1 at T23 is crucial for maintaining Cdc5 levels during G2 phase. This phosphorylation also prevents protein toxicity by capping accumulation of Cdc5 and CLB2 proteins.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Cdc5 (polo kinase/Plk1) is a conserved regulator of the yeast cell cycle.
- Mechanisms governing Cdc5 regulation are not fully understood.
- Cdc5 undergoes phosphorylation at multiple sites during mitosis.
Purpose of the Study:
- Investigate the function of the T23 phosphorylation site on Cdc5.
- Determine the role of Cdk1 (Cdc28) in Cdc5 regulation.
Main Methods:
- Site-directed mutagenesis to create Cdc5T23A and Cdc5T23E mutants.
- Analysis of Cdc5 protein levels and cellular localization.
- Assessment of cell proliferation and Clb2 levels.
Main Results:
- Cdc5T23A mutation introduces a degron, reducing Cdc5 levels but allowing normal proliferation.
- Cdk1 kinase activity is essential for maintaining Cdc5 levels during G2.
- Cdc5T23E mutation results in hyperactive Cdc5, reduced Cdc5 levels (in trans), and decreased Clb2 levels.
Conclusions:
- Cdk1-mediated phosphorylation of Cdc5 at T23 is required for maintaining Cdc5 levels in G2.
- T23 phosphorylation by Cdk1 limits the accumulation of Cdc5 and CLB2 proteins, preventing potential toxicity.
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