Cytosolic pH regulates cell growth through distinct GTPases, Arf1 and Gtr1, to promote Ras/PKA and TORC1 activity

Mol Cell. 2014 Aug 7;55(3):409-21. doi: 10.1016/j.molcel.2014.06.002. Epub 2014 Jul 4.


Regulation of cell growth by nutrients is governed by highly conserved signaling pathways, yet mechanisms of nutrient sensing are still poorly understood. In yeast, glucose activates both the Ras/PKA pathway and TORC1, which coordinately regulate growth through enhancing translation and ribosome biogenesis and suppressing autophagy. Here, we show that cytosolic pH acts as a cellular signal to activate Ras and TORC1 in response to glucose availability. We demonstrate that cytosolic pH is sensitive to the quality and quantity of the available carbon source (C-source). Interestingly, Ras/PKA and TORC1 are both activated through the vacuolar ATPase (V-ATPase), which was previously identified as a sensor for cytosolic pH in vivo. V-ATPase interacts with two distinct GTPases, Arf1 and Gtr1, which are required for Ras and TORC1 activation, respectively. Together, these data provide a molecular mechanism for how cytosolic pH links C-source availability to the activity of signaling networks promoting cell growth.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • ADP-Ribosylation Factor 1 / metabolism*
  • ADP-Ribosylation Factor 1 / physiology
  • Cytosol / metabolism
  • Gene Expression Regulation, Fungal
  • Glucose / metabolism*
  • Monomeric GTP-Binding Proteins / metabolism*
  • Saccharomyces cerevisiae / metabolism*
  • Saccharomyces cerevisiae Proteins / metabolism*
  • Signal Transduction*
  • Transcription Factors / metabolism*
  • Vacuolar Proton-Translocating ATPases / metabolism*
  • ras Proteins / metabolism


  • Gtr1 protein, S cerevisiae
  • Saccharomyces cerevisiae Proteins
  • TORC1 protein complex, S cerevisiae
  • Transcription Factors
  • Vacuolar Proton-Translocating ATPases
  • ADP-Ribosylation Factor 1
  • Monomeric GTP-Binding Proteins
  • ras Proteins
  • Glucose