Pib2 and the EGO complex are both required for activation of TORC1

J Cell Sci. 2017 Nov 15;130(22):3878-3890. doi: 10.1242/jcs.207910. Epub 2017 Oct 9.


The TORC1 complex is a key regulator of cell growth and metabolism in Saccharomyces cerevisiae The vacuole-associated EGO complex couples activation of TORC1 to the availability of amino acids, specifically glutamine and leucine. The EGO complex is also essential for reactivation of TORC1 following rapamycin-induced growth arrest and for its distribution on the vacuolar membrane. Pib2, a FYVE-containing phosphatidylinositol 3-phosphate (PI3P)-binding protein, is a newly discovered and poorly characterized activator of TORC1. Here, we show that Pib2 is required for reactivation of TORC1 following rapamycin-induced growth arrest. Pib2 is required for EGO complex-mediated activation of TORC1 by glutamine and leucine as well as for redistribution of Tor1 on the vacuolar membrane. Therefore, Pib2 and the EGO complex cooperate to activate TORC1 and connect phosphoinositide 3-kinase (PI3K) signaling and TORC1 activity.

Keywords: EGO complex; Gtr1; Gtr2; Pib2; TORC1.

MeSH terms

  • Apoptosis Regulatory Proteins / physiology*
  • Autophagy
  • Enzyme Activation
  • Intracellular Membranes / enzymology
  • Phosphatidylinositol 3-Kinases / metabolism
  • Protein Transport
  • Saccharomyces cerevisiae / enzymology*
  • Saccharomyces cerevisiae Proteins / metabolism*
  • Saccharomyces cerevisiae Proteins / physiology*
  • Signal Transduction
  • Transcription Factors / metabolism*
  • Vacuoles / enzymology


  • Apoptosis Regulatory Proteins
  • MEH1 protein, S cerevisiae
  • Pib2 protein, S cerevisiae
  • Saccharomyces cerevisiae Proteins
  • TORC1 protein complex, S cerevisiae
  • Transcription Factors