Developmental protein involved in neurogenesis. Required for the formation of chordotonal organs and photoreceptors. Seems to bind to E boxes. Specifically required for the photoreceptor R8 selection. Efficient DNA binding requires dimerization with another bHLH protein. Forms a heterodimer with Daughterless. Proneural clusters and sense organ precursors of the chordotonal organs, optic furrow of the eye-antennal disk and developing brain lobe.