Reconstitution of human Arp2/3 complex reveals critical roles of individual subunits in complex structure and activity.

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.
Mesh Terms:
Actin-Related Protein 2, Actin-Related Protein 3, Actins, Cytoskeletal Proteins, Humans, Macromolecular Substances, Microfilaments, Models, Biological, Polymers, Protein Subunits, Recombinant Proteins
Mol. Cell
Date: Nov. 01, 2001
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