Alpha-Actin, sarcomeric

The antibody 5C5 which is directed against sarcomeric alpha-actin labels skeletal and heart muscle cells but not smooth muscle cells. In neoplasms it may be used as a marker of rhabdomyosarcoma. Movement of cell organelles, cells, and organisms depends on the interaction of the cytoskeletal proteins actin and myosin. In birds and mammals up to now six different isoforms of actin have been identified using amino acid sequence analysis and electrophoresis. They are more or less specific for different organs resp. cell types. Four isoforms are known to occur in muscle cells, while two other forms are found in most other cell types. Alpha-Actin sarcomeric (a-sr-1) specific for skeletal- and heart-muscle.