Expression

• Staining showed a mainly cytoplasmic distrubition in three regions: the atrioventricular (AV) canal cushion tissue, the primitive ventricle, and conal crests. PMID: 7894148

• Sarcomeric actin genes, alpha-cardiac and alpha-skeletal, are coexpressed in neonatal rodent hearts and are regulated in response to hormonal and hemodynamic stimuli. PMID: 1568307

• we have immunocytochemically localized smooth and sarcomeric (cardiac and skeletal) alpha-actin in Hamburger-Hamilton (H-H) stage 7-18 embryos using monoclonal antibodies. Within the developing embryo at stage 9-, smooth muscle alpha-actin was exclusively detected in the developing heart, upon fusion of the endocardial tubes; sarcomeric alpha-actin was observed later (stage 9). By the onset of contraction at stage 10+, intense immunostaining of both smooth and sarcomeric isoproteins was observed in the ventricle; at this time smooth muscle alpha-actin was also detected in splanchnic mesoderm of the pre-vitelline area, in a cellular layer adjacent to the only embryonic cells that exhibited factor VIII (von Willebrand factor) antigens. Double immunostaining of the myocardium at stage 11, at which time striations were first detected, revealed the co-existence of smooth and sarcomeric actin in developing sarcomeres. Intense expression of sarcomeric actin continued in the heart after stage 11, whereas smooth muscle alpha-actin was down-regulated in the ventricle and became regionalized to the inflow and outflow tracts. As expected, smooth muscle alpha-actin was detected around intra- and extra-embryonic vascular structures at later developmental stages, while sarcomeric actin was observed in somites. PMID: 1581600

• In the two species, coexpression of alpha-sr and alpha-sm actins has been observed in cardiomyoblasts, myotomal myoblasts and myotubes. PMID: 2283002

• a second, sarcomeric muscle-specific alpha-actin isoform is expressed in serum-deprived BC3H1 myocytes and that the induction of this actin isoform occurs late in differentiation well after the observed upregulation of vascular alpha-actin synthesis. The sarcomeric alpha-actin was identified in myocytes on the basis of the unique electrophoretic mobility of its NH2-terminal tryptic peptide, the distribution of cleavage products that were obtained when the NH2-terminal tryptic peptide was subjected to secondary proteolytic cleavage with thermolysin and Staphylococcus aureus V8 protease, and the presence of an additional cysteine residue at the NH2 terminus of the biosynthetic precursor of this novel alpha-actin. PMID: 2470744

Function

• a sarcomeric actin can participate in the formation of Triton X-100-insoluble cytoskeletal structures. PMID: 6538118

Applications

Immunofluorescence (IF)

• Immunofluorescence of sarcomeric a-actin was enhanced and its expression increased dose- and time-dependently in T3-treated cultured heart myocytes. PMID: 15571324

Immunohistochemistry (IHC)

• Expression of vimentin, desmin, alpha-sarcomeric and alpha-smooth muscle actins in embryonic tissues of rat and mice was examined using an immunohistochemical approach. PMID: 2283002