Reconstitution of Human Arp2/3 Complex Reveals Critical Roles of Individual Subunits in Complex Structure and Activity

Mol Cell. 2001 Nov;8(5):1041-52. doi: 10.1016/s1097-2765(01)00393-8.

Abstract

The Arp2/3 complex is a seven-protein assembly that is critical for actin nucleation and branching in cells. Here we report the reconstitution of active human Arp2/3 complex after expression of all seven subunits in insect cells. Expression of partial complexes revealed that a heterodimer of the p34 and p20 subunits constitutes a critical structural core of the complex, whereas the remaining subunits are peripherally located. Arp3 is crucial for nucleation, consistent with it being a structural component of the nucleation site. p41, p21, and p16 contribute differently to nucleation and stimulation by ActA and WASP, whereas p34/p20 bind actin filaments and likely function in actin branching. This study reveals that the nucleating and organizing functions of Arp2/3 complex subunits are separable, indicating that these activities may be differentially regulated in cells.

Publication types

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

MeSH terms

  • Actin Cytoskeleton / metabolism*
  • Actin Cytoskeleton / ultrastructure
  • Actin-Related Protein 2
  • Actin-Related Protein 3
  • Actins / chemistry
  • Actins / isolation & purification
  • Actins / metabolism*
  • Cytoskeletal Proteins*
  • Humans
  • Macromolecular Substances
  • Models, Biological
  • Polymers / chemistry
  • Protein Subunits
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / isolation & purification
  • Recombinant Proteins / metabolism

Substances

  • ACTR2 protein, human
  • ACTR3 protein, human
  • Actin-Related Protein 2
  • Actin-Related Protein 3
  • Actins
  • Cytoskeletal Proteins
  • Macromolecular Substances
  • Polymers
  • Protein Subunits
  • Recombinant Proteins