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Nature Cell Biology 3, 699–707 (1 August 2001) | doi:10.1038/35087009

ActA and human zyxin harbour Arp2/3-independent actin-polymerization activity

Julie Fradelizi , Vincent Noireaux , Julie Plastino , Bernadette Menichi , Daniel Louvard , C|[eacute]|cile Sykes , Roy M. Golsteyn & Evelyne Friederich

The actin cytoskeleton is a dynamic network that is composed of a variety of F-actin structures. To understand how these structures are produced, we tested the capacity of proteins to direct actin polymerization in a bead assay in vitro and in a mitochondrial-targeting assay in cells. We found that human zyxin and the related protein ActA of Listeria monocytogenes can generate new actin structures in a vasodilator-stimulated phosphoprotein-dependent (VASP) manner, but independently of the Arp2/3 complex. These results are consistent with the concept that there are multiple actin-polymerization machines in cells. With these simple tests it is possible to probe the specific function of proteins or identify novel molecules that act upon cellular actin polymerization.