Involved in the establishment and dorsoventral patterning of germ layers in the embryo. Efficient DNA binding requires dimerization with another bHLH protein. Homodimer. Interacts with akirin (PubMed:22396663). Expressed in embryonic abdomen; a single cell ventrally, pairs of cells laterally and three cells dorsally in each hemisegment. In the thorax, there are patches of cells associated with the imaginal disks. During larval development, cells proliferate and, in the abdomen, they form ventral, lateral and dorsal clusters, which are the precursors of the adult abdominal muscles. In the thorax, they form populations of cells in the imaginal disks that correspond to the adepithelial cells. Expressed throughout development. Embryos fail to form the ventral furrow at gastrulation and lack mesoderm and all internal organs.