The mammalian target of rapamycin phosphorylates sites having a (Ser/Thr)-Pro motif and is activated by antibodies to a region near its COOH terminus.

Journal Article (Journal Article)

The eukaryotic initiation factor 4E (eIF4E)-binding protein, PHAS-I, was phosphorylated rapidly and stoichiometrically when incubated with [gamma-32P]ATP and the mammalian target of rapamycin (mTOR) that had been immunoprecipitated with an antibody, mTAb1, directed against a region near the COOH terminus of mTOR. PHAS-I was phosphorylated more slowly by mTOR obtained either by immunoprecipitation with other antibodies or by affinity purification using a rapamycin/FKBP12 resin. Adding mTAb1 to either of these preparations of mTOR increased PHAS-I phosphorylation severalfold, indicating that mTAb1 activates the mTOR protein kinase. mTAb1-activated mTOR phosphorylated Thr36, Thr45, Ser64, Thr69, and Ser82 in PHAS-I. All five of these sites fit a (Ser/Thr)-Pro motif and are dephosphorylated in response to rapamycin in rat adipocytes. Thus, our findings indicate that Pro is a determinant of the mTOR protein kinase specificity and that mTOR contributes to the phosphorylation of PHAS-I in cells.

Full Text

Duke Authors

Cited Authors

  • Brunn, GJ; Fadden, P; Haystead, TA; Lawrence, JC

Published Date

  • December 19, 1997

Published In

Volume / Issue

  • 272 / 51

Start / End Page

  • 32547 - 32550

PubMed ID

  • 9405468

International Standard Serial Number (ISSN)

  • 0021-9258

Digital Object Identifier (DOI)

  • 10.1074/jbc.272.51.32547


  • eng

Conference Location

  • United States