The mTOR/PI3K and MAPK pathways converge on eIF4B to control its phosphorylation and activity

David Shahbazian, Philippe P. Roux, Virginie Mieulet, Michael S. Cohen, Brian Raught, Jack Taunton, John W.B. Hershey, John Blenis, Mario Pende, Nahum Sonenberg

Research output: Contribution to journalArticlepeer-review

400 Scopus citations


The eukaryotic translation initiation factor 4B (eIF4B) plays a critical role in recruiting the 40S ribosomal subunit to the mRNA. In response to insulin, eIF4B is phosphorylated on Ser422 by S6K in a rapamycin-sensitive manner. Here we demonstrate that the p90 ribosomal protein S6 kinase (RSK) phosphorylates eIF4B on the same residue. The relative contribution of the RSK and S6K modules to the phosphorylation of eIF4B is growth factor-dependent, and the two phosphorylation events exhibit very different kinetics. The S6K and RSK proteins are members of the AGC protein kinase family, and require PDK1 phosphorylation for activation. Consistent with this requirement, phosphorylation of eIF4B Ser422 is abrogated in PDK1 null embryonic stem cells. Phosphorylation of eIF4B on Ser422 by RSK and S6K is physiologically significant, as it increases the interaction of eIF4B with the eukaryotic translation initiation factor 3.

Original languageEnglish (US)
Pages (from-to)2781-2791
Number of pages11
JournalEMBO Journal
Issue number12
StatePublished - Jun 21 2006
Externally publishedYes


  • Crosstalk
  • Phosphorylation
  • Signaling
  • Translation
  • eIF4B

ASJC Scopus subject areas

  • Neuroscience(all)
  • Molecular Biology
  • Biochemistry, Genetics and Molecular Biology(all)
  • Immunology and Microbiology(all)


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