The present invention concerns a novel cytoskeletal protein, myotilin, which contains Ig-like domains homologous to a giant sarcomeric structural protein titin. Myotilin is expressed in skeletal and cardiac muscles, it colocalizes with alpha -actinin in the sarcomeric I-bands and directly interacts with alpha -actinin. Expression of myotilin in mammalian non-muscle cells and in yeast causes reorganization of actin into thick F-actin bundles and inhibits growth of yeast cells.
