The Rheb switch 2 segment is critical for signaling to target of rapamycin complex 1

Xiaomeng Long, Yenshou Lin, Sara Ortiz-Vega, Susann Busch, Joseph Avruch*


研究成果: 雜誌貢獻期刊論文同行評審

38 引文 斯高帕斯(Scopus)


The small GTPase Rheb is a positive upstream regulator of the target of rapamycin (TOR) complex 1 in mammalian cells and can bind directly to TOR complex 1. To identify the regions of the Rheb surface most critical for signaling to TOR complex 1, we created a set of 26 mutants wherein clusters of 1-5 putative solvent-exposed residues were changed to alanine, ultimately changing 65 residues distributed over the entire Rheb surface. The signaling function of these mutants was assessed by their ability, in comparison to wild type Rheb, to restore the phosphorylation of S6K1(Thr389) when expressed transiently in amino acid-deprived 293T cells. The major finding is that two mutants situated in the Rheb switch 2 segment, Y67A/I69A and I76A/D77A, exhibit a near total loss of function, whereas extensive replacement of the switch 1 segment and other surface residues with alanines causes relatively little disturbance of Rheb rescue of S6K1 from amino acid withdrawal. This is surprising in view of the minimal impact of guanyl nucleotide on Rheb switch 2 configuration. The loss of function Rheb switch 2 mutants are well expressed and exhibit partial agonist function in amino acid-replete cells. They are unimpaired in their ability to bind GTP or mammalian (m)TOR in vivo or in vitro, and the mTOR polypeptides retrieved with these inactive Rheb mutants exhibit kinase activity in vitro comparable with mTOR bound to wild type Rheb. We conclude that Rheb signaling to mTOR in vivo requires a Rheb switch 2-dependent interaction with an element other than the three known polypeptide components of TOR complex 1.

頁(從 - 到)18542-18551
期刊Journal of Biological Chemistry
出版狀態已發佈 - 2007 6月 22

ASJC Scopus subject areas

  • 生物化學
  • 分子生物學
  • 細胞生物學


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