Arp2/3 complex is a seven-subunit
protein complex that plays a major role in the regulation of the
actin cytoskeleton. It is a major component of the
actin cytoskeleton and is found in most actin cytoskeleton-containing
eukaryotic cells. Two of its subunits, the
Actin-
Related
Proteins ARP2 and ARP3 closely resemble the structure of monomeric actin and serve as nucleation sites for new actin filaments. The complex binds to the sides of existing ("mother") filaments and initiates growth of a new ("daughter") filament at a distinctive 70 degree angle from the mother. Branched actin networks are created as a result of this nucleation of new filaments. The regulation of rearrangements of the actin cytoskeleton is important for processes like cell locomotion,
phagocytosis, and intracellular motility of
lipid vesicles.