The present invention relates to a muscle-specific protein, Ozz, and nucleic acids encoding the protein, that regulates development and function of muscle cells. The invention further relates to muscle-specific regulated expression of the protein, and of heterologous genes under control of the same regulatory sequences. In a specific example, a murine Ozz protein of 285 amino acids is preferentially expressed by a 1.0 kb mRNA in heart and skeletal muscle. This protein shares significant homology with neuralized proteins, and associates with a number of muscle proteins, including .beta.-catenin.