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Human p53 is phosphorylated by p60-cdc2 and cyclin B-cdc2
J R Bischoff1, P N Friedman, D R Marshak
1Howard Hughes Medical Institute, Cold Spring Harbor Laboratory, NY 11724.
Summary
The cell division cycle 2 (cdc2) enzyme phosphorylates the p53 tumor suppressor protein at serine-315. This phosphorylation is cell cycle-dependent and may regulate p53
Area of Science:
- Cell Biology
- Molecular Biology
- Oncology
Background:
- The p53 protein acts as an anti-oncoprotein, crucial for tumor suppression.
- Cell cycle regulation involves complex protein interactions and modifications.
Purpose of the Study:
- To investigate the relationship between p53 and the cell division cycle 2 (cdc2) enzyme.
- To identify the specific site and conditions of p53 phosphorylation by cdc2.
Main Methods:
- Western blotting to detect protein levels.
- Analysis of protein phosphorylation sites.
- Cell cycle synchronization and analysis.
Main Results:
- p53 is a direct substrate of cdc2, with serine-315 being the primary phosphorylation site.
- Phosphorylation occurs via both p60-cdc2 and cyclin B-cdc2 complexes.
- p53 abundance and phosphorylation exhibit cell cycle-dependent oscillations, peaking in G1 phase.
Conclusions:
- cdc2-mediated phosphorylation of p53 at serine-315 is a cell cycle-regulated event.
- This modification may play a role in regulating the antiproliferative functions of p53.