Actin Related Protein 2/3 Complex Subunit 3 (ARPC3)

ARPC3 encodes one of seven subunits of the human Arp2/3 protein complex. The ARC21 cDNA encodes a deduced 178-amino acid protein that is 45% identical to its homolog in S. cerevisiae. ARC21 localizes to the lamellipodia of stationary and motile fibroblasts, as well as to the actin tails assembled by Listeria monocytogenes. ARC21 was not detected in cellular bundles of actin filaments.cerevisiae Arp2/3 complexes bound to the WASP carboxy-terminal domain. Asymmetric, oblate ellipsoids were revealed. Image analysis of actin branches indicated that the complex binds the side of the mother filament, and ARP2 and ARP3 are the first 2 subunits of the daughter filament. Comparison to the actin-free WASP-activated complexes suggests that branch initiation involves large-scale structural rearrangements within ARP2/3.