Alpha-skeletal muscle actin (α-SMA) is a key contractile protein predominantly expressed in skeletal muscle cells, where it forms part of the thin filaments in sarcomeres, enabling muscle contraction. As one of six actin isoforms in mammals, α-SMA belongs to the actin family of cytoskeletal proteins and is encoded by the *ACTA1* gene. It plays a critical role in maintaining skeletal muscle structure, force generation, and mechanotransduction.
Antibodies targeting α-SMA are widely used as research tools to identify and study skeletal muscle cells in developmental biology, regenerative medicine, and disease models. These antibodies are particularly valuable in distinguishing skeletal muscle fibers from smooth or cardiac muscle (which express α-cardiac or β-cytoplasmic actin isoforms) via immunohistochemistry, immunofluorescence, or Western blotting. They are also employed in investigating pathological conditions such as muscular dystrophies, myopathies, and sarcopenia, where α-SMA expression may be altered.
Importantly, some α-SMA antibodies may cross-react with smooth muscle actin (e.g., in myofibroblasts) due to sequence homology, necessitating rigorous validation using controls like knockout tissues or cell lines. Monoclonal antibodies (e.g., clones 1A4. α-sr-1) are commonly used for specificity. Beyond research, α-SMA antibodies have diagnostic applications in differentiating muscle tumor subtypes. Their utility in tracking muscle regeneration, satellite cell activation, and fibrosis underscores their importance in both basic and translational muscle biology.