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Raptor, a binding partner of target of rapamycin

Kazuyoshi Yonezawa1, Chiharu Tokunaga, Noriko Oshiro

  • 1Biosignal Research Center, Kobe University, Kobe 657-8501, Japan. yonezawa@kobe-u.ac.jp

Biochemical and Biophysical Research Communications
|December 20, 2003
PubMed

Insights

Regulatory associated protein of mTOR (Raptor) acts as a scaffold protein, binding mTOR substrates like p70 S6 kinase alpha and 4EBP1. This binding is crucial for mTOR-mediated cell growth regulation.

Area of Science:

  • Cellular Biology
  • Molecular Signaling
  • Biochemistry

Background:

  • The mammalian target of rapamycin (mTOR) pathway regulates cell growth.
  • mTOR signaling is influenced by nutrients like amino acids and growth factors.
  • Key substrates of mTOR include p70 S6 kinase alpha (p70α) and eukaryotic initiation factor 4E binding protein 1 (4EBP1).

Purpose of the Study:

  • To elucidate the role of Raptor in mTOR signaling.
  • To understand how Raptor mediates the binding of mTOR substrates.
  • To identify upstream regulators of the mTOR-Raptor complex.

Main Methods:

  • The study focuses on the interactions between mTOR, Raptor, and its substrates.
  • Analysis of TOR signaling (TOS) motifs in substrate binding.
  • Investigating the role of Raptor as a scaffold protein.

Main Results:

  • Raptor, an mTOR binding protein, is essential for in vivo TOR signaling.
  • Raptor binds 4EBP1 and p70α via their TOS motifs.
  • Raptor functions as an mTOR scaffold, facilitating substrate phosphorylation.

Conclusions:

  • Raptor binding to the TOS motif is necessary for mTOR-catalyzed phosphorylation of substrates.
  • Understanding mTOR-Raptor complex regulation requires studying its interplay with upstream effectors like TSC1/2 and Rheb.

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