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Updated: Jan 9, 2026
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Identification of Cyclin-dependent Kinase 1 Specific Phosphorylation Sites by an In Vitro Kinase Assay
Published on: May 3, 2018
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Mechanism of RPA phosphocode priming and tuning by CDK1/WEE1 signaling circuit
Poonam Roshan1, Vikas Kaushik2, Ayush Mistry2
1Department of Biology, Saint Louis University, St. Louis, MO, USA.
Nature Communications
|December 9, 2025
Summary
Replication protein A (RPA) phosphorylation by CDK1 on RPA70 is key for cell cycle and DNA repair. This priming mechanism enhances RPA32 hyperphosphorylation, regulating cell fate.
Area of Science:
- Molecular Biology
- Cell Biology
- Biochemistry
Background:
- Replication protein A (RPA) is vital for DNA metabolism and repair.
- RPA32 hyperphosphorylation, primed by cyclin-dependent kinase (CDK), regulates DNA damage response.
- The precise mechanisms of RPA priming and its cell cycle role are unclear.
Purpose of the Study:
- To investigate the role of RPA70 phosphorylation by CDK1.
- To elucidate the mechanism of RPA priming and its impact on DNA damage response.
- To understand the RPA-CDK axis in cell cycle regulation.
Main Methods:
- Site-directed mutagenesis
- Phosphorylation assays
- Cell cycle analysis
- Kinase activity assays
- Structural analysis
Main Results:
- CDK1 phosphorylates RPA70 at Thr-191, essential for G2 to M transition.
- RPA70 Thr-191 phosphorylation stabilizes WEE1 kinase, creating a feedback loop for CDK1.
- This modification primes RPA32 for hyperphosphorylation, enhancing DNA damage response.
- CDK1-mediated phosphorylation reconfigures RPA structure, facilitating further phosphorylation.
Conclusions:
- A novel phosphocode-dependent feedback mechanism links RPA and kinases.
- RPA phosphorylation by CDK1 has dual roles in cell cycle progression and DNA repair.
- This intricate regulation ensures proper cellular response to DNA damage and division.
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