Alpha-actinin structure and regulation.

Alpha-actinin is a cytoskeletal actin-binding protein and a member of the spectrin superfamily, which comprises spectrin, dystrophin and their homologues and isoforms. It forms an anti-parallel rod-shaped dimer with one actin-binding domain at each end of the rod and bundles actin filaments in multiple cell-type and cytoskeleton frameworks. In non-muscle cells, alpha-actinin is found along the actin filaments and in adhesion sites. In striated, cardiac and smooth muscle cells, it is localized at the Z-disk and analogous dense bodies, where it forms a lattice-like structure and stabilizes the muscle contractile apparatus. Besides binding to actin filaments alpha-actinin associates with a number of cytoskeletal and signaling molecules, cytoplasmic domains of transmembrane receptors and ion channels, rendering it important structural and regulatory roles in cytoskeleton organization and muscle contraction. This review reports on the current knowledge on structure and regulation of alpha-actinin.