Exo70 interacts with phospholipids and mediates the targeting of the exocyst to the plasma membrane

EMBO J. 2007 Sep 19;26(18):4053-65. doi: 10.1038/sj.emboj.7601834. Epub 2007 Aug 23.


The exocyst is an octameric protein complex implicated in the tethering of post-Golgi secretory vesicles to the plasma membrane before fusion. The function of individual exocyst components and the mechanism by which this tethering complex is targeted to sites of secretion are not clear. In this study, we report that the exocyst subunit Exo70 functions in concert with Sec3 to anchor the exocyst to the plasma membrane. We found that the C-terminal Domain D of Exo70 directly interacts with phosphatidylinositol 4,5-bisphosphate. In addition, we have identified key residues on Exo70 that are critical for its interaction with phospholipids and the small GTPase Rho3. Further genetic and cell biological analyses suggest that the interaction of Exo70 with phospholipids, but not Rho3, is essential for the membrane association of the exocyst complex. We propose that Exo70 mediates the assembly of the exocyst complex at the plasma membrane, which is a crucial step in the tethering of post-Golgi secretory vesicles for exocytosis.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actins / metabolism
  • Alleles
  • Cell Membrane / metabolism*
  • Models, Biological
  • Multiprotein Complexes / metabolism*
  • Mutation / genetics
  • Phosphatidylinositol 4,5-Diphosphate
  • Phospholipids / metabolism*
  • Phosphotransferases (Alcohol Group Acceptor)
  • Phosphotransferases / metabolism
  • Protein Binding
  • Protein Structure, Tertiary
  • Protein Subunits / metabolism
  • Saccharomyces cerevisiae / cytology
  • Saccharomyces cerevisiae / growth & development
  • Saccharomyces cerevisiae / metabolism*
  • Saccharomyces cerevisiae Proteins / chemistry
  • Saccharomyces cerevisiae Proteins / metabolism*
  • Vesicular Transport Proteins
  • rho GTP-Binding Proteins / metabolism


  • Actins
  • EXO70 protein, S cerevisiae
  • Multiprotein Complexes
  • Phosphatidylinositol 4,5-Diphosphate
  • Phospholipids
  • Protein Subunits
  • SEC3 protein, S cerevisiae
  • Saccharomyces cerevisiae Proteins
  • Vesicular Transport Proteins
  • Phosphotransferases
  • Phosphotransferases (Alcohol Group Acceptor)
  • MSS4 protein, S cerevisiae
  • RHO3 protein, S cerevisiae
  • rho GTP-Binding Proteins