Capping protein increases the rate of actin-based motility by promoting filament nucleation by the Arp2/3 complex

Cell. 2008 May 30;133(5):841-51. doi: 10.1016/j.cell.2008.04.011.


Capping protein (CP) is an integral component of Arp2/3-nucleated actin networks that drive amoeboid motility. Increasing the concentration of capping protein, which caps barbed ends of actin filaments and prevents elongation, increases the rate of actin-based motility in vivo and in vitro. We studied the synergy between CP and Arp2/3 using an in vitro actin-based motility system reconstituted from purified proteins. We find that capping protein increases the rate of motility by promoting more frequent filament nucleation by the Arp2/3 complex and not by increasing the rate of filament elongation as previously suggested. One consequence of this coupling between capping and nucleation is that, while the rate of motility depends strongly on the concentration of CP and Arp2/3, the net rate of actin assembly is insensitive to changes in either factor. By reorganizing their architecture, dendritic actin networks harness the same assembly kinetics to drive different rates of motility.

Publication types

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

MeSH terms

  • Actin Capping Proteins / isolation & purification
  • Actin Capping Proteins / metabolism*
  • Actin Cytoskeleton / metabolism
  • Actin Depolymerizing Factors / isolation & purification
  • Actin Depolymerizing Factors / metabolism
  • Actin-Related Protein 2-3 Complex / isolation & purification
  • Actin-Related Protein 2-3 Complex / metabolism*
  • Actins / isolation & purification
  • Actins / metabolism*
  • Animals
  • Bacterial Proteins / isolation & purification
  • Bacterial Proteins / metabolism
  • Brain Chemistry
  • Cattle
  • Cell Movement*
  • Cell-Free System
  • Kinetics
  • Listeria monocytogenes
  • Membrane Proteins / isolation & purification
  • Membrane Proteins / metabolism
  • Microspheres
  • Polystyrenes / metabolism
  • Profilins / isolation & purification
  • Profilins / metabolism


  • Actin Capping Proteins
  • Actin Depolymerizing Factors
  • Actin-Related Protein 2-3 Complex
  • Actins
  • Bacterial Proteins
  • Membrane Proteins
  • Polystyrenes
  • Profilins
  • actA protein, Listeria monocytogenes