ARP3/YJR065C Summary Help

Standard Name ARP3 1
Systematic Name YJR065C
Alias ACT4
Feature Type ORF, Verified
Description Essential component of the Arp2/3 complex; Arp2/3 is a highly conserved actin nucleation center required for the motility and integrity of actin patches; involved in endocytosis and membrane growth and polarity (1, 2, 3 and see Summary Paragraph)
Name Description Actin-Related Protein 1
Chromosomal Location
ChrX:559158 to 557809 | ORF Map | GBrowse
Note: this feature is encoded on the Crick strand.
Gene Ontology Annotations All ARP3 GO evidence and references
  View Computational GO annotations for ARP3
Molecular Function
Manually curated
Biological Process
Manually curated
Cellular Component
Manually curated
Regulators 4 genes
Classical genetics
reduction of function
Large-scale survey
reduction of function
143 total interaction(s) for 70 unique genes/features.
Physical Interactions
  • Affinity Capture-MS: 57
  • Affinity Capture-RNA: 3
  • Affinity Capture-Western: 21
  • Co-fractionation: 2
  • Co-purification: 5
  • Reconstituted Complex: 5
  • Two-hybrid: 1

Genetic Interactions
  • Dosage Rescue: 1
  • Negative Genetic: 25
  • Phenotypic Enhancement: 1
  • Phenotypic Suppression: 1
  • Positive Genetic: 14
  • Synthetic Growth Defect: 1
  • Synthetic Haploinsufficiency: 1
  • Synthetic Lethality: 5

Expression Summary
Length (a.a.) 449
Molecular Weight (Da) 49,541
Isoelectric Point (pI) 5.6
Phosphorylation PhosphoGRID | PhosphoPep Database
sequence information
ChrX:559158 to 557809 | ORF Map | GBrowse
Note: this feature is encoded on the Crick strand.
Last Update Coordinates: 2011-02-03 | Sequence: 1996-07-31
Subfeature details
Most Recent Updates
Coordinates Sequence
CDS 1..1350 559158..557809 2011-02-03 1996-07-31
Retrieve sequences
Analyze Sequence
S288C only
S288C vs. other species
S288C vs. other strains
External Links All Associated Seq | Entrez Gene | Entrez RefSeq Protein | MIPS | Search all NCBI (Entrez) | UniProtKB
Primary SGDIDS000003826

ARP3, an essential gene, encodes an actin-related protein (33% identical to yeast actin encoded by ACT1) that functions as part of a highly conserved actin-nucleation complex (3; for review see 4). This complex, termed the Arp2/3 complex, localizes to regions of actin-based motility, such as the actin comet tails of Listeria (5) and the leading edges of motile amoebae (Acanthoamoeba) and fibroblast cells (6, 7, 8). In S. cerevisiae, the Arp2/3 complex is required for actin-dependent processes such as endocytosis and organelle inheritance (9; for review, see 10). Arp3p localizes to actin cortical patches (2). At the restrictive temperature, a conditional arp3 mutant allele inhibits actin patch motility and eventually disrupts actin patches, giving rise to aberrant actin structures (2).

The Arp2/3 complex is a seven-protein complex containing two actin-related proteins, Arp2p and Arp3p, and five non-actin related proteins, Arc15p, Arc18p, Arc19p, Arc35p, and Arc40p (2). The Arp2/3 complex nucleates the formation of branched actin filaments by binding to the side of an existing (mother) filament and nucleating the formation of a new (daughter) actin filament at a 70 degree angle (11). Arp2p and Arp3p serve as the first two subunits of the daughter filament, likely mimicking actin monomers due to their structural similarity to actin (12). However, the Arp2/3 complex does not play a role in the formation of actin cables (unbranched actin structures), which are instead nucleated by the formins Bni1p and Bnr1p (13, 14).

To achieve optimal actin nucleation activity, the Arp2/3 complex interacts with an activator protein, such as Las17p/Bee1p (of the SCAR/WASp family), myosin I, Abp1p, or Pan1p (for reviews, see 15, 16). In vitro studies have shown that the activator protein alters the conformation of the Arp2/3 complex, as to bringing Arp2p and Arp3p together in a "filamentous" arrangement to mimic an actin dimer (12).

Last updated: 2003-11-25 Contact SGD

References cited on this page View Complete Literature Guide for ARP3
1) Poch O and Winsor B  (1997) Who's who among the Saccharomyces cerevisiae actin-related proteins? A classification and nomenclature proposal for a large family. Yeast 13(11):1053-8
2) Winter D, et al.  (1997) The complex containing actin-related proteins Arp2 and Arp3 is required for the motility and integrity of yeast actin patches. Curr Biol 7(7):519-29
3) Huang ME, et al.  (1996) Identification of ACT4, a novel essential actin-related gene in the yeast Saccharomyces cerevisiae. Yeast 12(9):839-48
4) Machesky LM and Gould KL  (1999) The Arp2/3 complex: a multifunctional actin organizer. Curr Opin Cell Biol 11(1):117-21
5) Welch MD, et al.  (1997) Actin polymerization is induced by Arp2/3 protein complex at the surface of Listeria monocytogenes. Nature 385(6613):265-9
6) Welch MD, et al.  (1997) The human Arp2/3 complex is composed of evolutionarily conserved subunits and is localized to cellular regions of dynamic actin filament assembly. J Cell Biol 138(2):375-84
7) Machesky LM, et al.  (1994) Purification of a cortical complex containing two unconventional actins from Acanthamoeba by affinity chromatography on profilin-agarose. J Cell Biol 127(1):107-15
8) Kelleher JF, et al.  (1995) Sequences, structural models, and cellular localization of the actin-related proteins Arp2 and Arp3 from Acanthamoeba. J Cell Biol 131(2):385-97
9) Boldogh IR, et al.  (2001) Arp2/3 complex and actin dynamics are required for actin-based mitochondrial motility in yeast. Proc Natl Acad Sci U S A 98(6):3162-7
10) Goode BL and Rodal AA  (2001) Modular complexes that regulate actin assembly in budding yeast. Curr Opin Microbiol 4(6):703-12
11) Mullins RD, et al.  (1997) Structure, subunit topology, and actin-binding activity of the Arp2/3 complex from Acanthamoeba. J Cell Biol 136(2):331-43
12) Volkmann N, et al.  (2001) Structure of Arp2/3 complex in its activated state and in actin filament branch junctions. Science 293(5539):2456-9
13) Evangelista M, et al.  (2002) Formins direct Arp2/3-independent actin filament assembly to polarize cell growth in yeast. Nat Cell Biol 4(1):32-41
14) Sagot I, et al.  (2002) An actin nucleation mechanism mediated by Bni1 and profilin. Nat Cell Biol 4(8):626-31
15) Olazabal IM and Machesky LM  (2001) Abp1p and cortactin, new "hand-holds" for actin. J Cell Biol 154(4):679-82
16) Schafer DA  (2002) Coupling actin dynamics and membrane dynamics during endocytosis. Curr Opin Cell Biol 14(1):76-81