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Activation of protein phosphatase 2A by the Fe2+/ascorbate system
1Department of Cell and Molecular Biology, Institute of Basic Medicine, Medical College of Chang Gung University, Tao-Yuan, Taiwan, Republic of China. yusong@mail.cgu.edu.tw
Journal of Biochemistry
|June 30, 1998
Summary
The Fe2+/ascorbate system activates latent protein phosphatase 2A (PP2A). This finding suggests iron ions may be a biological cofactor for PP2A activation, crucial for cellular processes.
Area of Science:
- Biochemistry
- Enzymology
- Molecular Biology
Background:
- Protein phosphatase 2A (PP2A) is essential for dephosphorylation but loses activity upon storage, becoming latent.
- Latent PP2A requires specific ions like Mn2+ or Co2+ for reactivation.
Purpose of the Study:
- To investigate the activation of latent PP2A using the Fe2+/ascorbate system.
- To determine the role of Fe2+ and ascorbate in PP2A activation.
Main Methods:
- Biochemical assays measuring PP2A activity.
- Testing the effect of Fe2+/ascorbate system on both PP2A holoenzyme and catalytic subunit.
- Evaluating the impact of various metal ions and reducing/oxidizing agents.
Main Results:
- The Fe2+/ascorbate system effectively activated latent PP2A.
- Activation was dependent on Fe2+ and ascorbate concentrations.
- Dithiothreitol mimicked ascorbate, while H2O2 inhibited activation.
- Both PP2A holoenzyme and catalytic subunit were activated.
Conclusions:
- Fe2+ ions, stabilized by reducing agents like ascorbate, can activate latent PP2A.
- Fe2+ may function as a biologically relevant metal ion cofactor for PP2A.
- Direct modulation of PP2A's catalytic subunit by Fe2+/ascorbate is a potential mechanism.