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Updated: Jun 18, 2026

Identification of Kinase-substrate Pairs Using High Throughput Screening
11:13

Identification of Kinase-substrate Pairs Using High Throughput Screening

Published on: August 29, 2015

Rictor is a novel target of p70 S6 kinase-1

C Treins1, P H Warne, M A Magnuson

  • 1Signal Transduction Laboratory, Cancer Research UK London Research Institute, London, UK.

Oncogene
|November 26, 2009
PubMed

Insights

Researchers found that Rictor, a protein in mTOR complex-2 (mTORC2), is phosphorylated by S6K1. This phosphorylation regulates mTORC2 interactions, influenced by nutrients and growth factors.

Area of Science:

  • Cellular Biology
  • Molecular Signaling
  • Biochemistry

Background:

  • The mammalian target of rapamycin (mTOR) complex-2 (mTORC2) is crucial for cell signaling, phosphorylating AGC kinases.
  • Rictor is a key component of mTORC2, regulating its activity.
  • Understanding mTORC2 regulation is vital for comprehending cellular responses to nutrients and growth factors.

Purpose of the Study:

  • To identify novel phosphorylation sites on Rictor.
  • To investigate the signaling pathways regulating Rictor phosphorylation.
  • To determine the functional consequences of Rictor phosphorylation, particularly at Thr1135.

Main Methods:

  • Phosphoproteomic analysis to identify novel phosphorylation sites on Rictor.
  • Biochemical assays to confirm Rictor as a direct target of S6K1.
  • Site-directed mutagenesis to study the role of Thr1135 phosphorylation.
  • Analysis of 14-3-3 protein binding to Rictor and mTORC2.

Main Results:

  • Several novel Rictor phosphorylation sites were identified, including the conserved Thr1135.
  • Rictor is a direct substrate of ribosomal protein S6 kinase-1 (S6K1).
  • Phosphorylation of Rictor at Thr1135 is regulated by amino acids and growth factors via a rapamycin-sensitive pathway.
  • Thr1135 phosphorylation mediates 14-3-3 binding to Rictor and mTORC2, impacting complex interactions without altering kinase activity.

Conclusions:

  • Rictor phosphorylation by S6K1 represents an unexpected signaling input into mTORC2.
  • This regulatory mechanism allows mTORC2 to integrate signals from amino acids and growth factors.
  • The dynamic regulation of Rictor phosphorylation and subsequent 14-3-3 binding provides a mechanism for modulating mTORC2 complex interactions.

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