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Sunday 7 March 2004


Definition : Microfilaments are involved in cell motility, organelle transport, cytokinesis, and muscle contraction. Microfilaments are linear polymers of actin. The actin cytoskeleton plays critical roles in cell morphologic changes and motility.


- alpha-actins: ACTA1, ACTA2
- beta-actins: ACTB
- cardiac-actins: ACTC
- gamma-actins: ACTG

The cadherin-catenin system

The formation of cadherin-mediated cell-cell junctions is accompanied by a profound remodeling of the actin cytoskeleton. The Arp2/3 complex and its activator cortactin drive the assembly of branching actin-filament arrays, and formin-1 promotes the nucleation of non-branching actin filaments.

Recruitment of these actin nucleators to nascent adhesions, formation of the links between them and the cytoplasmic cadherin domain, and triggering of their actin-polymerizing functions are vital steps in the development of cell-cell junctions.


Rho family small GTPases, such as Rho (MIM.165370), RAC (MIM.602048), and CDC42 (MIM.116952), organize the actin cytoskeleton. Other major players in actin-based motility are the 7 members of the ARP2/3 complex (MIM.604221).

The Wiskott-Aldrich syndrome protein (WASP) (MIM.301000), WASP-like (WASL) (MIM.605056), and WASF1 are among the downstream effector molecules involved in the transmission of signals from tyrosine kinase receptors and small GTPases to the actin cytoskeleton.


- Wiskott-Aldrich syndrome and WASP mutations

- congenital myopathies

See also:

- actin-related proteins (ARPs )

  • Arp2/3 complex

- actin-binding proteins
- cytoskeleton


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- Blessing CA, Ugrinova GT, Goodson HV. Actin and ARPs: action in the nucleus. Trends Cell Biol. 2004 Aug;14(8):435-42. PMID: 15308210

- Finkelstein LD, Schwartzberg PL. Tec kinases: shaping T-cell activation through actin. Trends Cell Biol. 2004 Aug;14(8):443-51. PMID: 15308211

- Behrendt B. FAP52 - a new partner for filamin in actin cytoskeleton organization. Trends Cell Biol. 2002 May;12(5):213. PMID: 12062164

- Rottner K, Lommel S, Wehland J, Stradal TE. Pathogen-induced actin filament rearrangement in infectious diseases. J Pathol. 2004 Nov;204(4):396-406. Review.
PMID: 15495265

- Clarkson E, Costa CF, Machesky LM. Congenital myopathies: diseases of the actin cytoskeleton. J Pathol. 2004 Nov;204(4):407-17. PMID: 15495263