Description
Smooth Muscle Actin belongs to the actin family of proteins, which are highly conserved proteins that play a role in cell motility, structure and integrity. Alpha, beta and gamma actin isoforms have been identified, with alpha actin being a major constituent of the contractile apparatus, while beta and gamma actins are involved in the regulation of cell motility. In particular, smooth muscle actin is an alpha actin that is found in skeletal muscle. Actin exists as a ubiquitous protein involved with filament formation that make up large portions of the cytoskeleton. Actin filaments interact with myosin to assist in muscle contraction as well as aiding in cell motility and cytokinesis. Smooth muscle actin is found on smooth muscle vessel walls, gut wall, myometrium, myoepithelial cells in breast and salivary glands. Defects in the smooth muscle actin gene cause aortic aneurysm familial thoracic type 6. Actin isoforms differ slightly in their N-terminus and the sequences of each are perfectly conserved in higher vertebrates. Alpha-smooth muscle actin is abundant in vascular and visceral smooth muscle cells. In addition, it has also been shown that smooth muscle actin appear in stress fibers of fibroblastic cells during pathological situations involving contractile phenomena such as wound healing and fibrocontractive diseases. Multiple alternatively spliced variants of smooth muscle actin have been identified