Acts as a transcriptional regulator. Involved in postembryonic mesodermal cell fate specification. Activates ceh-24 and egl-15 during mesodermal patterning. Efficient DNA binding requires dimerization with another bHLH protein. Homodimer. Forms a heterodimer with hlh-2. Expressed in defecation-associated muscles and neuron-like cells in the head at the L1 stage. In later larvae, expressed in SM cells and their descendants. Not expressed in differentiated body wall or sex muscles.