The ARP2/3 complex: an actin nucleator comes of age

The ARP2/3 complex regulates the initiation of actin polymerization and the organization of filaments into y-branched networks. Recent studies have begun to reveal the role of this complex in diverse cellular processes and its molecular mechanisms of action, as well as its misregulation during disease. The cellular functions of the actin cytoskeleton require precise regulation of both the initiation of actin polymerization and the organization of the resulting filaments. The actin-related protein-2/3 (ARP2/3) complex is a central player in this regulation. A decade of study has begun to shed light on the molecular mechanisms by which this powerful machine controls the polymerization, organization and recycling of actin-filament networks, both in vitro and in the living cell.