The mTOR (mammalian target of rapamycin) protein kinase is an important regulator of cell growth. Two complexes of mTOR have been identified: complex 1, consisting of mTOR–Raptor (regulatory associated protein of mTOR)–mLST8 (termed mTORC1), and complex 2, comprising mTOR–Rictor (rapamycininsensitive companion of mTOR)–mLST8–Sin1 (termed mTORC2). mTORC1 phosphorylates the p70 ribosomal S6K (S6 kinase) at its hydrophobic motif (Thr389), whereas mTORC2 phosphorylates PKB (protein kinase B) at its hydrophobic motif (Ser473). In the present study, we report that widely expressed isoforms of unstudied proteins termed Protor-1 (protein observed with Rictor-1) and Protor-2 interact with Rictor and are components of mTORC2. We demonstrate that immunoprecipitation of Protor-1 or Protor-2 results in the co-immunoprecipitation of other mTORC2 subunits, but not Raptor, a specific component of mTORC1. We show that detergents such as Triton X-100 or n-octylglucoside dissociate mTOR and mLST8 from a complex of Protor-1, Sin1 and Rictor. We also provide evidence that Rictor regulates the expression of Protor-1, and that Protor-1 is not required for the assembly of other mTORC2 subunits into a complex. Protor-1 is a novel Rictor-binding subunit of mTORC2, but further work is required to establish its role.
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August 2007
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Research Article|
July 13 2007
Identification of Protor as a novel Rictor-binding component of mTOR complex-2
Laura R. Pearce;
*MRC Protein Phosphorylation Unit, School of Life Sciences, MSI/WTB Complex, University of Dundee, Dundee DD1 5EH, Scotland, U.K.
2To whom correspondence should be addressed (email l.r.pearce@dundee.ac.uk).
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Xu Huang;
Xu Huang
1
*MRC Protein Phosphorylation Unit, School of Life Sciences, MSI/WTB Complex, University of Dundee, Dundee DD1 5EH, Scotland, U.K.
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Jérôme Boudeau;
Jérôme Boudeau
*MRC Protein Phosphorylation Unit, School of Life Sciences, MSI/WTB Complex, University of Dundee, Dundee DD1 5EH, Scotland, U.K.
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Rafał Pawłowski;
Rafał Pawłowski
*MRC Protein Phosphorylation Unit, School of Life Sciences, MSI/WTB Complex, University of Dundee, Dundee DD1 5EH, Scotland, U.K.
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Stephan Wullschleger;
Stephan Wullschleger
*MRC Protein Phosphorylation Unit, School of Life Sciences, MSI/WTB Complex, University of Dundee, Dundee DD1 5EH, Scotland, U.K.
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Maria Deak;
Maria Deak
*MRC Protein Phosphorylation Unit, School of Life Sciences, MSI/WTB Complex, University of Dundee, Dundee DD1 5EH, Scotland, U.K.
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Adel F. M. Ibrahim;
Adel F. M. Ibrahim
*MRC Protein Phosphorylation Unit, School of Life Sciences, MSI/WTB Complex, University of Dundee, Dundee DD1 5EH, Scotland, U.K.
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Robert Gourlay;
Robert Gourlay
*MRC Protein Phosphorylation Unit, School of Life Sciences, MSI/WTB Complex, University of Dundee, Dundee DD1 5EH, Scotland, U.K.
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Mark A. Magnuson;
Mark A. Magnuson
†Department of Molecular Physiology and Biophysics and Centre for Stem Cell Biology, Vanderbilt University School of Medicine, Nashville, TN 37232, U.S.A.
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Dario R. Alessi
Dario R. Alessi
*MRC Protein Phosphorylation Unit, School of Life Sciences, MSI/WTB Complex, University of Dundee, Dundee DD1 5EH, Scotland, U.K.
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Publisher: Portland Press Ltd
Received:
April 23 2007
Accepted:
April 27 2007
Accepted Manuscript online:
April 27 2007
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© The Authors Journal compilation © 2007 Biochemical Society
2007
Biochem J (2007) 405 (3): 513–522.
Article history
Received:
April 23 2007
Accepted:
April 27 2007
Accepted Manuscript online:
April 27 2007
Citation
Laura R. Pearce, Xu Huang, Jérôme Boudeau, Rafał Pawłowski, Stephan Wullschleger, Maria Deak, Adel F. M. Ibrahim, Robert Gourlay, Mark A. Magnuson, Dario R. Alessi; Identification of Protor as a novel Rictor-binding component of mTOR complex-2. Biochem J 1 August 2007; 405 (3): 513–522. doi: https://doi.org/10.1042/BJ20070540
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