GbetaL, a positive regulator of the rapamycin-sensitive pathway required for the nutrient-sensitive interaction between raptor and mTOR

Mol Cell. 2003 Apr;11(4):895-904. doi: 10.1016/s1097-2765(03)00114-x.

Abstract

mTOR and raptor are components of a signaling pathway that regulates mammalian cell growth in response to nutrients and growth factors. Here, we identify a member of this pathway, a protein named GbetaL that binds to the kinase domain of mTOR and stabilizes the interaction of raptor with mTOR. Like mTOR and raptor, GbetaL participates in nutrient- and growth factor-mediated signaling to S6K1, a downstream effector of mTOR, and in the control of cell size. The binding of GbetaL to mTOR strongly stimulates the kinase activity of mTOR toward S6K1 and 4E-BP1, an effect reversed by the stable interaction of raptor with mTOR. Interestingly, nutrients and rapamycin regulate the association between mTOR and raptor only in complexes that also contain GbetaL. Thus, we propose that the opposing effects on mTOR activity of the GbetaL- and raptor-mediated interactions regulate the mTOR pathway.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adaptor Proteins, Signal Transducing
  • Amino Acid Sequence / genetics
  • Base Sequence / genetics
  • Carrier Proteins / genetics
  • Carrier Proteins / isolation & purification*
  • Carrier Proteins / metabolism
  • Cell Differentiation / physiology*
  • Cell Size
  • Eukaryotic Cells / metabolism*
  • HeLa Cells
  • Humans
  • Intracellular Signaling Peptides and Proteins*
  • Macromolecular Substances
  • Molecular Sequence Data
  • Phosphoproteins / metabolism
  • Protein Binding / physiology
  • Protein Kinases / metabolism*
  • Protein Structure, Tertiary / physiology
  • Protein Subunits / genetics
  • Protein Subunits / isolation & purification*
  • Proteins / genetics
  • Proteins / isolation & purification*
  • Proteins / metabolism*
  • Regulatory-Associated Protein of mTOR
  • Ribosomal Protein S6 Kinases, 70-kDa / metabolism
  • Signal Transduction / physiology*
  • Sirolimus / pharmacology
  • TOR Serine-Threonine Kinases
  • Tacrolimus Binding Proteins / metabolism
  • mTOR Associated Protein, LST8 Homolog

Substances

  • Adaptor Proteins, Signal Transducing
  • Carrier Proteins
  • EIF4EBP1 protein, human
  • Intracellular Signaling Peptides and Proteins
  • MLST8 protein, human
  • Macromolecular Substances
  • Phosphoproteins
  • Protein Subunits
  • Proteins
  • RPTOR protein, human
  • Regulatory-Associated Protein of mTOR
  • mTOR Associated Protein, LST8 Homolog
  • Protein Kinases
  • MTOR protein, human
  • TOR Serine-Threonine Kinases
  • Ribosomal Protein S6 Kinases, 70-kDa
  • ribosomal protein S6 kinase, 70kD, polypeptide 2
  • Tacrolimus Binding Proteins
  • Sirolimus