Overview:

Actin, a ubiquitous protein in eukaryotes, is the major component of the cytoskeleton. At least six isoforms are known in mammals. Nonmuscle beta- and gamma-actin, also known as cytoplasmic actin, are predominantly expressed in nonmuscle cells, controling cell structure and motility (1). alpha-cardiac and alpha-skeletal actin are expressed in striated cardiac and skeletal muscles, respectively; two smooth muscle actins, alpha- and gamma-actin, are found primarily in vascular smooth muscle and enteric smooth muscle, respectively. These actin isoforms regulate contractile potentials for muscle cells (1).

References:

1. Herman, I.M. (1993) Curr. Opin. Cell Biol. 5, 48–55.