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Updated: Jul 15, 2026
08:05
Assaying Protein Kinase Activity with Radiolabeled ATP
Published on: May 26, 2017
Clamping the Mec1/ATR checkpoint kinase into action
Jerzy Majka1, Peter M J Burgers
1Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
Cell Cycle (Georgetown, Tex.)
|May 15, 2007
Summary
The Mec1/ATR kinase, crucial for cell cycle checkpoints, is activated by interacting factors, not DNA damage directly. These factors, like the Rad17-Mec3-Ddc1 clamp and TopBP1, signal DNA damage or replication stress to Mec1/ATR.
Area of Science:
- Cell Biology
- Molecular Biology
- Genetics
Background:
- Mec1/ATR is a key regulator of cell cycle checkpoints in response to DNA damage and replication stress.
- Mec1/ATR activity is not directly controlled by DNA substrates but by interacting factors.
- Understanding Mec1/ATR regulation is crucial for comprehending DNA repair and cell cycle control.
Purpose of the Study:
- To elucidate the regulatory mechanisms of Mec1/ATR activation.
- To identify the factors involved in transducing DNA damage and replication stress signals to Mec1/ATR.
- To investigate the roles of the Rad17-Mec3-Ddc1 complex and TopBP1 in Mec1/ATR activation.
Main Methods:
- Investigated protein-DNA interactions in yeast and vertebrate cell models.
- Utilized genetic and biochemical assays to study checkpoint protein function.
- Analyzed the kinase activity of Mec1/ATR in response to various cellular stresses.
Main Results:
- The DNA damage checkpoint clamp Rad17-Mec3-Ddc1 (human 9-1-1) is loaded onto gapped DNA and its Ddc1 subunit activates Mec1.
- TopBP1 (Cut5/Dpb11) activates ATR in vertebrate cells during replication fork dysfunction.
- Both activation pathways lead to a general upregulation of Mec1/ATR kinase activity.
Conclusions:
- Mec1/ATR activation relies on signal transduction through interacting factors, not direct DNA binding.
- The Rad17-Mec3-Ddc1 complex and TopBP1 are critical mediators of Mec1/ATR activation in response to DNA damage and replication stress.
- These findings provide insights into the conserved mechanisms of DNA damage response and cell cycle regulation across species.
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