The cytoskeleton is a fibrous meshwork of three major components – actin microfilaments, microtubules and intermediate filaments. These are assembled from soluble precursors, under precise control by many different cellular processes. Other proteins interlink filaments or travel along with them. The cytoskeleton is found in all eukaryotic cells, and is required both for the maintenance of cell structure and for the organization of many aspects of cell movement.

Keywords: actin; tubulin; intermediate filament; microtubule; cell motility

Figure 1.

The three major classes of cytoskeletal filaments: (a) microfilaments (composed of actin monomers); (b) microtubules (composed of α‐ and β‐tubulin); (c) intermediate filaments (various different types of monomer).

Figure 2.

Polymerization of actin. (a) The rate of polymerization or depolymerization depends on the actin monomer concentration. Note that each end behaves differently. The critical concentration for each end is the concentration of actin monomers at which there is no net polymerization or depolymerization. (b) Kinetics of polymerization of an actin solution above the critical concentration for barbed ends. The long delay is caused by the slow formation of three‐subunit nuclei.

Figure 3.

Contrasting actin‐rich structures. (a) Microvilli. In these long finger‐like structures on the surfaces of absorptive epithelia, the actin filaments are bundled in the same direction (isotropically). (b) Lamellipodium. The actin‐rich edges at the leading edges of motile cells contain actin filaments crosslinked at an angle to one another.


Further Reading

Bray D (1992) Cell Movements. New York: Garland.

Desai A and Mitchison TJ (1998) Microtubule polymerization dynamics. Annual Review of Cell and Development Biology 13: 83–117.

Fuchs E (1996) The cytoskeleton and disease: genetic disorders of intermediate filaments. Annual Review of Genetics 30: 197–231.

Schmidt A and Hall MN (1998) Signalling to the actin cytoskeleton. Annual Review of Cell and Developmental Biology 14: 305–338.

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How to Cite close
Insall, Robert, and Machesky, Laura(Apr 2001) Cytoskeleton. In: eLS. John Wiley & Sons Ltd, Chichester. [doi: 10.1038/npg.els.0001252]