Actin Cytoskeleton

Definition

The actin cytoskeleton is a network of actin and actin binding proteins that together with the other components of the cytoskeleton such as microtubules and intermediate filaments is responsible for essential cellular processes like cell migration, axonal growth, phagocytosis, cytoplasmic streaming and organelle transport (1, 2). It was first isolated as a part of the actomyosin complex from muscle cells. Actin was subsequently identified in all eukaryotic cells. Its most characteristic feature is the reversible polymerization of globular actin monomers (G-actin) into filaments (F-actin) that build either a relatively permanent structure as in sarcomeres of fully differentiated muscle cells or, in nearly all other cell types, a continuously restructured filamentous meshwork. Given its role in many essential cellular processes, the amino acid sequence of actin is highly conserved throughout evolution. Deletion of the single actin gene in yeast is lethal. In many other...