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Updated: Jul 17, 2026
06:56
Development and Application of Rapamycin-regulated Tyrosine Phosphatases
Published on: September 6, 2024
Phosphatase targets in TOR signaling
1Department of Physiology and Biophysics, UMDNJ, Robert Wood Johnson Medical School, Piscataway, NJ, USA.
Methods in Molecular Biology (Clifton, N.J.)
|January 4, 2007
Summary
Nutrient sensing involves the target of rapamycin (TOR) pathway, which regulates cell growth. In yeast, TOR controls the SIT4 phosphatase, influencing protein synthesis and turnover via NPR1 and TIP41 phosphorylation.
Area of Science:
- Cellular biology
- Molecular signaling
- Biochemistry
Background:
- Cellular growth is regulated by nutrient availability.
- The target of rapamycin (TOR) is a central signaling kinase responding to nutrients.
- TOR controls protein synthesis and turnover, crucial for cell mass.
- In yeast, TOR signaling is linked to the SIT4 phosphatase activity.
Purpose of the Study:
- To elucidate the regulatory mechanism of TOR signaling in yeast.
- To investigate the role of SIT4 phosphatase in TOR-mediated growth control.
- To establish a readout for TOR and SIT4 activity.
Main Methods:
- Yeast genetics and molecular biology techniques.
- Analysis of protein phosphorylation states.
- Assays for TOR and SIT4 pathway activity.
Main Results:
- TOR signaling promotes phosphorylation of downstream targets, enhancing protein synthesis.
- TOR negatively regulates SIT4 phosphatase activity by promoting its association with TAP42.
- Inactivation of TOR leads to SIT4-dependent dephosphorylation of NPR1 and TIP41.
- Phosphorylation status of NPR1 and TIP41 serves as a reliable indicator of TOR and SIT4 activity.
Conclusions:
- TOR signaling integrates nutrient availability with cell growth control.
- The TOR-SIT4-TAP42 axis is a key regulatory pathway in yeast.
- NPR1 and TIP41 phosphorylation provide a facile method to monitor TOR and SIT4 pathway status.
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