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ATM gene product phosphorylates I kappa B-alpha
M Jung1, A Kondratyev, S A Lee
1Department of Radiation Medicine, Vincent T. Lombardi Cancer Center, Georgetown University Medical Center, Washington, DC 20007, USA.
Cancer Research
|January 1, 1997
Summary
The ATM gene, mutated in ataxia telangiectasia, functions as a protein kinase. This ATM protein phosphorylates I kappa B-alpha, suggesting a role in NF-kappa B activation.
Area of Science:
- Genetics
- Molecular Biology
- Biochemistry
Background:
- The ATM gene is mutated in ataxia telangiectasia patients, but its function is unknown.
- ATM shares sequence similarity with phosphatidyl-3 kinase catalytic domains.
- ATM is a large protein (approximately 350,000 M(r)) present in normal cells but absent in ataxia telangiectasia cells.
Purpose of the Study:
- To determine the biological functions of the ATM gene.
- To investigate the enzymatic activity of the ATM protein.
- To explore ATM's potential role in cellular signaling pathways.
Main Methods:
- Generated rabbit polyclonal antibodies against ATM protein.
- Confirmed ATM protein presence and size using immunoprecipitation and Western blotting.
- Assessed kinase activity of immunoprecipitated ATM protein in vitro.
Main Results:
- ATM protein (approximately 350,000 M(r)) was detected in normal cells and absent in ataxia telangiectasia cells.
- Immunoprecipitated ATM protein demonstrated in vitro kinase activity, phosphorylating I kappa B-alpha.
- ATM did not exhibit phosphatidyl-3 kinase or DNA-dependent protein kinase activity.
Conclusions:
- ATM possesses protein kinase activity.
- ATM may play a role in the activation of NF-kappa B.
- These findings provide insights into the molecular mechanisms underlying ataxia telangiectasia.