Arp2/3 complex
 Cryo-EM structure of the Arp2/3 complex at a branched-actin junction. (PDB: 7TPT) | |
| Overview | |
|---|---|
| Synonyms | ARP2/3, Actin-related protein 2/3 complex |
| Subunits | Arp2, Arp3, ARPC1A, ARPC1B, ARPC2, ARPC3, ARPC4, ARPC5 |
| Molecular mass | ~224 kDa |
| Class | Actin binding proteins |
| Functions | Actin cross-linking Actin branching Actin polymerization |
| Biological context | |
| Organism(s) | Eukaryota |
| Location | Cytoplasm |
| Pathways | WASP-Arp2/3 pathway |
| Processes | Synaptic plasticity Cell migration Endocytosis Morphogenesis |
| Identifiers & Data | |
| PDB structures | 7TPT |
| EMDB ID | EMD-46993 |
| Complex Portal | CPX-2592 |
Arp2/3 complex (Actin Related Protein 2/3 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 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 the intracellular motility of lipid vesicles.
The Arp2/3 complex was identified in 1994 (preliminarily described as "unconventional actins") by affinity chromatography from the human pathogen Acanthamoeba castellanii, though it had been previously isolated in 1989 in a search for proteins that bind to actin filaments in Drosophila melanogaster embryos.