Phosphoinositides and membrane curvature switch the mode of actin polymerization via selective recruitment of toca-1 and Snx9 Academic Article uri icon


MeSH Major

  • Actins
  • Carrier Proteins
  • Cell Membrane
  • Phosphatidylinositols
  • Polymerization
  • Sorting Nexins
  • Xenopus Proteins


  • The membrane-cytosol interface is the major locus of control of actin polymerization. At this interface, phosphoinositides act as second messengers to recruit membrane-binding proteins. We show that curved membranes, but not flat ones, can use phosphatidylinositol 3-phosphate [PI(3)P] along with phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] to stimulate actin polymerization. In this case, actin polymerization requires the small GTPase cell cycle division 42 (Cdc42), the nucleation-promoting factor neural Wiskott-Aldrich syndrome protein (N-WASP) and the actin nucleator the actin-related protein (Arp) 2/3 complex. In liposomes containing PI(4,5)P2 as the sole phosphoinositide, actin polymerization requires transducer of Cdc42 activation-1 (toca-1). In the presence of phosphatidylinositol 3-phosphate, polymerization is both more efficient and independent of toca-1. Under these conditions, sorting nexin 9 (Snx9) can be implicated as a specific adaptor that replaces toca-1 to mobilize neural Wiskott-Aldrich syndrome protein and the Arp2/3 complex. This switch in phosphoinositide and adaptor specificity for actin polymerization from membranes has implications for how different types of actin structures are generated at precise times and locations in the cell.

publication date

  • April 30, 2013



  • Academic Article



  • eng

PubMed Central ID

  • PMC3645562

Digital Object Identifier (DOI)

  • 10.1073/pnas.1305286110

PubMed ID

  • 23589871

Additional Document Info

start page

  • 7193

end page

  • 8


  • 110


  • 18