Structure and function of the Arp2/3 complex

The Arp2/3 complex is a ubiquitous and essential component of the actin cyt oskeleton in eukaryotic cells. It nucleates actin filaments, caps their poi nted ends and cross-links them into orthogonal networks. In amoeba, vertebr ates and fungi, the complex consists of actin-related proteins Arp2 and Arp 3 and individual copies of five novel polypeptides. The Arps are thought to mediate pointed-end capping and nucleation. Chemical cross-linking implica tes three subunits in binding the complex to the side of another actin fila ment.