Raptor and mTOR: subunits of a nutrient-sensitive complex

Curr Top Microbiol Immunol. 2004;279:259-70. doi: 10.1007/978-3-642-18930-2_15.


mTOR/RAFT1/FRAP is the target of the FKBP12-rapamycin complex as well as a central component of a nutrient- and hormone-sensitive pathway that controls cellular growth. Recent work reveals that mTOR interacts with a novel evolutionarily conserved protein that we named raptor, for "regulatory associated protein of mTOR." Raptor has several roles in the mTOR pathway. It is necessary for nutrient-mediated activation of the downstream effector S6K1 and increases in cell size. In addition, under conditions that repress the mTOR pathway, the association of raptor with mTOR is strengthened, leading to a decrease in mTOR kinase activity. Raptor is a critical component of the mTOR pathway that regulates cell growth in response to nutrient levels by associating with mTOR.

Publication types

  • Review

MeSH terms

  • Adaptor Proteins, Signal Transducing
  • Conserved Sequence
  • Humans
  • Protein Kinases / metabolism*
  • Proteins / metabolism*
  • Regulatory-Associated Protein of mTOR
  • Signal Transduction / physiology
  • Sirolimus / metabolism
  • Sirolimus / pharmacology
  • TOR Serine-Threonine Kinases


  • Adaptor Proteins, Signal Transducing
  • Proteins
  • RPTOR protein, human
  • Regulatory-Associated Protein of mTOR
  • Protein Kinases
  • MTOR protein, human
  • TOR Serine-Threonine Kinases
  • Sirolimus