The scaffolding protein GRASP/Tamalin directly binds to Dock180 as well as to cytohesins facilitating GTPase crosstalk in epithelial cell migration

BMC Cell Biol. 2013 Feb 26;14:9. doi: 10.1186/1471-2121-14-9.


Background: The transition of epithelial cells from their normal non-motile state to a motile one requires the coordinated action of a number of small GTPases. We have previously shown that epithelial cell migration is stimulated by the coordinated activation of Arf and Rac GTPases. This crosstalk depends upon the assembly of a multi-protein complex that contains the Arf-activating protein cytohesin 2/ARNO and the Rac activating protein Dock180. Two scaffolding proteins that bind directly to cytohesin 2 organize this complex.

Results: We now have found that Rac activation in response to hepatocyte growth factor (HGF) requires cytohesin 2 and Dock180. GRASP/Tamalin is one of the scaffolds that builds the complex containing cytohesin 2 and Dock180. We determine here that the Ala/Pro rich region of GRASP directly interacts with the SH3 domain of Dock180. By binding to both cytohesin 2/ARNO and Dock180, GRASP bridges the guanine nucleotide exchange factors (GEFs) that activate Arf and Rac, thereby promoting Arf-to-Rac signaling. Furthermore, we find that knockdown of GRASP impairs hepatocyte growth factor (HGF)-stimulated Rac activation and HGF-stimulated epithelial migration.

Conclusions: GRASP binds directly both cytohesin 2 and Dock180 to coordinate their activities, and by doing so promotes crosstalk between Arf and Rac.

Publication types

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

MeSH terms

  • ADP-Ribosylation Factors / metabolism
  • Animals
  • Carrier Proteins / antagonists & inhibitors
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism*
  • Cell Movement / drug effects
  • Dogs
  • Enzyme Activation / drug effects
  • GTP Phosphohydrolases / metabolism*
  • GTPase-Activating Proteins / metabolism*
  • HEK293 Cells
  • Hepatocyte Growth Factor / pharmacology
  • Humans
  • Madin Darby Canine Kidney Cells
  • Membrane Proteins / antagonists & inhibitors
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism*
  • Protein Binding
  • RNA Interference
  • RNA, Small Interfering / metabolism
  • Signal Transduction
  • rac GTP-Binding Proteins / metabolism*
  • rac1 GTP-Binding Protein / metabolism
  • src Homology Domains


  • Carrier Proteins
  • DOCK1 protein, human
  • GTPase-Activating Proteins
  • Membrane Proteins
  • RNA, Small Interfering
  • cytohesin-2
  • tamalin protein, human
  • Hepatocyte Growth Factor
  • GTP Phosphohydrolases
  • ADP-Ribosylation Factors
  • ADP-ribosylation factor 6
  • rac GTP-Binding Proteins
  • rac1 GTP-Binding Protein