ACTA2 (actin alpha 2) is an
actin
Actin is a family of globular multi-functional proteins that form microfilaments in the cytoskeleton, and the thin filaments in muscle fibrils. It is found in essentially all eukaryotic cells, where it may be present at a concentration of ov ...
protein with several aliases including alpha-actin, alpha-actin-2, aortic smooth muscle or alpha smooth muscle actin (α-SMA, SMactin, alpha-SM-actin, ASMA).
Actin
Actin is a family of globular multi-functional proteins that form microfilaments in the cytoskeleton, and the thin filaments in muscle fibrils. It is found in essentially all eukaryotic cells, where it may be present at a concentration of ov ...
s are a
family of
globular
A globular cluster is a spheroidal conglomeration of stars. Globular clusters are bound together by gravity, with a higher concentration of stars towards their centers. They can contain anywhere from tens of thousands to many millions of membe ...
multi-functional
proteins that form
microfilament
Microfilaments, also called actin filaments, are protein filaments in the cytoplasm of eukaryotic cells that form part of the cytoskeleton. They are primarily composed of polymers of actin, but are modified by and interact with numerous other p ...
s. ACTA2 is one of 6 different actin
isoforms and is involved in the
contractile
Contractility refers to the ability for self-contraction, especially of the muscles or similar active biological tissue
*Contractile ring in cytokinesis
*Contractile vacuole
*Muscle contraction
**Myocardial contractility
*See contractile cell for ...
apparatus of
smooth muscle. ACTA2 (as with all the actins) is extremely
highly conserved
In evolutionary biology, conserved sequences are identical or similar sequences in nucleic acids ( DNA and RNA) or proteins across species ( orthologous sequences), or within a genome ( paralogous sequences), or between donor and receptor taxa ( ...
and found in nearly all mammals.
In humans, ACTA2 is encoded by the ''ACTA2''
gene located on 10q22-q24.
Mutations in this gene cause a variety of vascular diseases, such as thoracic aortic disease,
coronary artery disease,
stroke,
Moyamoya disease
Moyamoya disease is a disease in which certain arteries in the brain are constricted. Blood flow is blocked by constriction and blood clots (thrombosis). A collateral circulation develops around the blocked vessels to compensate for the blockage, ...
, and
multisystemic smooth muscle dysfunction syndrome
Multisystemic smooth muscle dysfunction syndrome (MSMDS) is a genetic disorder caused by R179 missense mutations in the ACTA2 gene. Initially described as a case report in 1999, it was characterized in 2010 as a syndrome of congenital mydriasis, p ...
.
ACTA2 (commonly referred to as alpha-smooth muscle actin or α-SMA) is often used as a marker of
myofibroblast formation.
Studies have shown that ACTA2 is associated with TGF β pathway that enhances contractile properties of Hepatic Stellate Cells leading to liver fibrosis and cirrhosis.
References
Further reading
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External links
GeneReviews/NIH/NCBI/UW entry on Thoracic Aortic Aneurysms and Aortic Dissections*
Human proteins
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