Structural conservation of components in the amino acid sensing branch of the TOR pathway in yeast and mammals

Konstantin Kogan, Eric D. Spear, Chris A. Kaiser, Deborah Fass

Research output: Contribution to journalArticlepeer-review

48 Scopus citations


The highly conserved Rag family GTPases have a role in reporting amino acid availability to the TOR (target of rapamycin) signaling complex, which regulates cell growth and metabolism in response to environmental cues. The yeast Rag proteins Gtr1p and Gtr2p were shown in multiple independent studies to interact with the membrane-associated proteins Gse1p (Ego3p) and Gse2p (Ego1p). However, mammalian orthologs of Gse1p and Gse2p could not be identified. We determined the crystal structure of Gse1p and found it to match the fold of two mammalian proteins, MP1 (mitogen-activated protein kinase scaffold protein 1) and p14, which form a heterodimeric complex that had been assigned a scaffolding function in mitogen-activated protein kinase pathways. The significance of this structural similarity is validated by the recent identification of a physical and functional association between mammalian Rag proteins and MP1/p14. Together, these findings reveal that key components of the TOR signaling pathway are structurally conserved between yeast and mammals, despite divergence of sequence to a degree that thwarts detection through simple homology searches.

Original languageEnglish (US)
Pages (from-to)388-398
Number of pages11
JournalJournal of molecular biology
Issue number2
StatePublished - Sep 2010
Externally publishedYes


  • Late endosome
  • Lysosome
  • Nutrient sensing
  • Scaffold proteins
  • TOR signaling

ASJC Scopus subject areas

  • Biophysics
  • Structural Biology
  • Molecular Biology


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