Very concise and informative reviews on the myofibrillar proteins have been published by Maruyama (1985), Squire and Vibert (1987), Nakai and Li-Chan (1988), and Morrissey, Mulvihill, and O’Neill (1987). They describe not only the chemical structure, properties, and location of myosin and actin, of the regulatory proteins, and of the scaffold proteins in the ultrastructure of muscles but also the functional characteristics of several of these proteins.