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Updated: May 9, 2026
05:28
A Semi-Quantitative Drug Affinity Responsive Target Stability (DARTS) assay for studying Rapamycin/mTOR interaction
Published on: August 27, 2019
mTORC1 phosphorylation sites encode their sensitivity to starvation and rapamycin.
Seong A Kang1, Michael E Pacold, Christopher L Cervantes
1Whitehead Institute for Biomedical Research, Nine Cambridge Center, Cambridge, MA 02142, USA.
Science (New York, N.Y.)
|July 27, 2013
Summary
The mechanistic target of rapamycin (mTOR) complex 1 (mTORC1) pathway
Area of Science:
- Cellular signaling pathways
- Molecular mechanisms of cell growth regulation
Background:
- The mechanistic target of rapamycin (mTOR) complex 1 (mTORC1) is a key regulator of cell growth.
- Rapamycin is a drug targeting mTORC1 that extends lifespan in model organisms, but its effects on substrate phosphorylation are not fully understood.
Purpose of the Study:
- To investigate why certain mTORC1 substrates are resistant to rapamycin.
- To identify the determinants of substrate sensitivity to mTORC1 pathway modulators.
Main Methods:
- In vitro kinase assays using peptides representing mTORC1 phosphorylation sites.
- Cellular experiments assessing substrate phosphorylation sensitivity to rapamycin and starvation.
Main Results:
- mTORC1 kinase activity varies significantly across different phosphorylation sites.
- In vitro activity strongly correlates with in-cell resistance to rapamycin and starvation.
- Minor modifications to phosphorylation sites alter mTORC1 activity and cellular sensitivity to pathway modulators.
Conclusions:
- Substrate quality, defined as the intrinsic capacity of a phosphorylation site to act as an mTORC1 substrate, is a key determinant of sensitivity to rapamycin and starvation.
- This finding reveals a mechanism for differential regulation of mTORC1 effectors by common signals.
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