May act as a transcriptional activator that promotes transcription of muscle-specific target genes and plays a role in muscle differentiation. Efficient DNA binding requires dimerization with another bHLH protein. From mid-gastrula to just before somite formation, expressed in cells adjacent to axial mesoderm. Subsequently, during the anterior-to-posterior wave of somite formation and maturation, expressed within particular regions of each somite. Expressed in both muscle and non-muscle cells.