The yeast phosphatidylinositol kinase homolog TOR2 activates RHO1 and RHO2 via the exchange factor ROM2

Cell. 1997 Feb 21;88(4):531-42. doi: 10.1016/s0092-8674(00)81893-0.

Abstract

The Saccharomyces cerevisiae phosphatidylinositol kinase homolog TOR2 is required for organization of the actin cytoskeleton. Overexpression of RHO1 or RHO2, encoding Rho-like GTPases, or ROM2, encoding a GDP/GTP exchange factor for RHO1 and RHO2, suppresses a tor2 mutation. Deletion of SAC7, a gene originally identified as a suppressor of an actin mutation, also suppresses a tor2 mutation. SAC7 is a novel GTPase-activating protein for RHO1. ROM2 exchange activity is reduced in a tor2 mutant, and overexpression of ROM2 lacking its PH domain can no longer suppress a tor2 mutation. Thus, TOR2 signals to the actin cytoskeleton through a GTPase switch composed of RHO1, RHO2, ROM2, and SAC7. TOR2 activates this switch via ROM2, possibly via the ROM2 PH domain.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Cycle Proteins
  • Cell Division / physiology
  • Cell Polarity / physiology
  • Cell Size / physiology
  • DNA-Binding Proteins / chemistry
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism*
  • Fungal Proteins / genetics
  • Fungal Proteins / metabolism*
  • GTP Phosphohydrolases / genetics
  • GTP Phosphohydrolases / metabolism
  • GTP-Binding Proteins / genetics
  • GTP-Binding Proteins / metabolism*
  • GTPase-Activating Proteins
  • Gene Expression Regulation, Enzymologic / physiology
  • Gene Expression Regulation, Fungal / physiology
  • Guanine Nucleotide Exchange Factors*
  • Guanosine Diphosphate / metabolism
  • Guanosine Triphosphate / metabolism
  • Leucine Zippers / physiology
  • Molecular Sequence Data
  • Monomeric GTP-Binding Proteins*
  • Mutation / physiology
  • Phosphatidylinositol 3-Kinases
  • Phosphotransferases (Alcohol Group Acceptor) / genetics
  • Phosphotransferases (Alcohol Group Acceptor) / metabolism*
  • Plant Proteins / chemistry
  • Plant Proteins / genetics
  • Plant Proteins / metabolism*
  • Protein Structure, Tertiary
  • Proteins / metabolism
  • Saccharomyces cerevisiae / cytology
  • Saccharomyces cerevisiae / enzymology*
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae Proteins*
  • Sequence Homology, Amino Acid
  • Signal Transduction / physiology
  • rho GTP-Binding Proteins*

Substances

  • Cell Cycle Proteins
  • DNA-Binding Proteins
  • Fungal Proteins
  • GTPase-Activating Proteins
  • Guanine Nucleotide Exchange Factors
  • Plant Proteins
  • Proteins
  • ROM2 protein, S cerevisiae
  • SAC7 protein, S cerevisiae
  • Saccharomyces cerevisiae Proteins
  • Guanosine Diphosphate
  • Guanosine Triphosphate
  • Phosphatidylinositol 3-Kinases
  • Phosphotransferases (Alcohol Group Acceptor)
  • TOR2 protein, S cerevisiae
  • GTP Phosphohydrolases
  • GTP-Binding Proteins
  • Monomeric GTP-Binding Proteins
  • RHO1 protein, S cerevisiae
  • RHO2 protein, S cerevisiae
  • rho GTP-Binding Proteins