Clone REA402 recognizes the sarcomeric α-actinin antigen, a 100 kDa actin-binding protein, which occupies a strategic role in the assembly and maintenance of stress fibers of non-muscle cells and the myofibrils of muscle cells. α-actinins have been highly conserved throughout evolution and are largely collinear proteins that share three conserved functional domains. Functionally, α-actinins form antiparallel homodimers with the actin-binding domains on each end of the molecule, allowing crosslinking of actin molecules. Two isoforms of α-actinin have been identified, a muscle-specific sarcomeric isoform and a non-sarcomeric isoform. The major – and best characterized – functional difference among α-actinin isoforms is calcium sensitivity for actin-binding. The binding of α-actinin to actin by non-muscle cytoskeletal isoforms is dependent on the calcium concentration, whereas this interaction is independent of calcium concentration in sarcomeric striated and smooth muscle isoforms. Studies on skeletal and cardiac cells have localized sarcomeric α-actinin to Z-bands in striated myofibrils, to precursor I-Z-I-like complexes in muscle undergoing myofibrillogenesis, and to vinculin-positive adhesion plaques and adherens junctions.

Additional information: Clone REA402 displays negligible binding to Fc receptors.