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Functional surfaces on the p35/ARPC2 subunit of Arp2/3 complex required for cell growth, actin nucleation, and endocytosis.

The Arp2/3 complex is comprised of seven evolutionarily conserved subunits and upon activation by WASp or another nucleation promoting factor nucleates the formation of actin filaments. These events are critical for driving a wide range of cellular processes, including motility, endocytosis, and intracellular trafficking. However, an in depth understanding of the Arp2/3 complex activation and nucleation mechanism is still lacking. Here, we used a mutagenesis approach in Saccharomyces cerevisiae to dissect the structural and functional roles of the p35/ARPC2 subunit. Using integrated alleles that target conserved and solvent-exposed residues, we identified surfaces on p35/ARPC2 required for cell growth, actin organization, and endocytosis. In parallel, we purified the mutant Arp2/3 complexes and compared their actin assembly activities both in the presence and in the absence of WASp. The majority of alleles with defects mapped to one face of p35/ARPC2, where there was a close correlation between loss of actin nucleation and endocytosis. A second site required for nucleation and endocytosis was identified near the contact surface between p35/ARPC2 and p19/ARPC4. A third site was identified at a more distal conserved surface, which was critical for endocytosis but not nucleation. These findings pinpoint the key surfaces on p35/ARPC2 required for Arp2/3 complex-mediated actin assembly and cellular function and provide a higher resolution view of Arp2/3 structure and mechanism.

Pubmed ID: 18381280


  • Daugherty KM
  • Goode BL


The Journal of biological chemistry

Publication Data

June 13, 2008

Associated Grants

  • Agency: NIGMS NIH HHS, Id: GM63691
  • Agency: NIGMS NIH HHS, Id: R01 GM063691
  • Agency: NIGMS NIH HHS, Id: T32 GM007596

Mesh Terms

  • Actin-Related Protein 2-3 Complex
  • Actins
  • Alleles
  • Amino Acid Sequence
  • Binding Sites
  • Cell Proliferation
  • Dose-Response Relationship, Drug
  • Endocytosis
  • Models, Biological
  • Molecular Conformation
  • Molecular Sequence Data
  • Mutagenesis
  • Phenotype
  • Plasmids
  • Saccharomyces cerevisiae