Alpha actinins are a diverse group of cytoskeletal proteins within the spectrin gene superfamily. This gene specifically encodes a muscle-specific alpha-actinin isoform expressed in skeletal and cardiac muscle. Unlike the cytoskeletal isoform found in nonmuscle cells that binds actin to the membrane, this muscle isoform is localized to the Z-disc, where it anchors myofibrillar actin filaments.