GRASP and IPCEF Promote ARF-to-Rac Signaling and Cell Migration by Coordinating the Association of ARNO/cytohesin 2 With Dock180

Mol Biol Cell. 2010 Feb 15;21(4):562-71. doi: 10.1091/mbc.e09-03-0217. Epub 2009 Dec 16.


ARFs are small GTPases that regulate vesicular trafficking, cell shape, and movement. ARFs are subject to extensive regulation by a large number of accessory proteins. The many different accessory proteins are likely specialized to regulate ARF signaling during particular processes. ARNO/cytohesin 2 is an ARF-activating protein that promotes cell migration and cell shape changes. We report here that protein-protein interactions mediated by the coiled-coil domain of ARNO are required for ARNO induced motility. ARNO lacking the coiled-coil domain does not promote migration and does not induce ARF-dependent Rac activation. We find that the coiled-coil domain promotes the assembly of a multiprotein complex containing both ARNO and the Rac-activating protein Dock180. Knockdown of either GRASP/Tamalin or IPCEF, two proteins known to bind to the coiled-coil of ARNO, prevents the association of ARNO and Dock180 and prevents ARNO-induced Rac activation. These data suggest that scaffold proteins can regulate ARF dependent processes by biasing ARF signaling toward particular outputs.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • ADP-Ribosylation Factors / genetics
  • ADP-Ribosylation Factors / metabolism*
  • Animals
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism*
  • Cell Adhesion Molecules / genetics
  • Cell Adhesion Molecules / metabolism*
  • Cell Line
  • Cell Movement / physiology*
  • Dogs
  • Enzyme Activation
  • GTPase-Activating Proteins / chemistry
  • GTPase-Activating Proteins / genetics
  • GTPase-Activating Proteins / metabolism*
  • Gene Knockdown Techniques
  • Humans
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism*
  • Multiprotein Complexes / chemistry
  • Multiprotein Complexes / metabolism
  • Protein Structure, Secondary
  • RNA, Small Interfering / genetics
  • RNA, Small Interfering / metabolism
  • Signal Transduction / physiology*
  • rac GTP-Binding Proteins / genetics
  • rac GTP-Binding Proteins / metabolism*


  • Carrier Proteins
  • Cell Adhesion Molecules
  • DOCK1 protein, human
  • GRASP protein, human
  • GTPase-Activating Proteins
  • IPCEF protein, human
  • Membrane Proteins
  • Multiprotein Complexes
  • RNA, Small Interfering
  • cytohesin-2
  • ADP-Ribosylation Factors
  • rac GTP-Binding Proteins