The exocyst is a Ral effector complex

Nat Cell Biol. 2002 Jan;4(1):66-72. doi: 10.1038/ncb728.


Delivery of cytoplasmic vesicles to discrete plasma-membrane domains is critical for establishing and maintaining cell polarity, neurite differentiation and regulated exocytosis. The exocyst is a multisubunit complex required for vectorial targeting of a subset of secretory vesicles. Mechanisms that regulate the activity of this complex in mammals are unknown. Here we show that Sec5, an integral component of the exocyst, is a direct target for activated Ral GTPases. Ral GTPases regulate targeting of basolateral proteins in epithelial cells, secretagogue-dependent exocytosis in neuroendocrine cells and assembly of exocyst complexes. These observations define Ral GTPases as critical regulators of vesicle trafficking.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Caco-2 Cells
  • Carrier Proteins / physiology
  • Cell Polarity / physiology
  • Exocytosis / physiology*
  • Fungal Proteins / physiology
  • GTPase-Activating Proteins*
  • HeLa Cells
  • Humans
  • Membrane Proteins / physiology*
  • PC12 Cells
  • Phospholipase D / physiology
  • Protein Transport / physiology
  • Rats
  • Secretory Vesicles / physiology
  • Signal Transduction*
  • Vesicular Transport Proteins
  • ral GTP-Binding Proteins / physiology*


  • Carrier Proteins
  • Exoc2 protein, rat
  • Fungal Proteins
  • GTPase-Activating Proteins
  • Membrane Proteins
  • Ralbp1 protein, rat
  • Vesicular Transport Proteins
  • Phospholipase D
  • phospholipase D1
  • ral GTP-Binding Proteins