Actin Related Protein 2/3 Complex Subunit 4 (ARPC4)

ARPC4 encodes one of seven subunits of the human Arp2/3 protein complex. The exact role of the protein encoded by this gene, the p20 subunit, has yet to be determined. Three transcript variants encoding two distinct isoforms have been found for this gene. The ARC20 cDNA encodes a deduced 168-amino acid protein that is 68% and 67% identical to its homologs in S. pombe and S. cerevisiae, respectively.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.