Probably acts as a transcriptional activator. Mediates neuronal differentiation. Required for the regulation of amacrine cell fate specification in the retina (By similarity). Efficient DNA binding requires dimerization with another bHLH protein (By similarity). Forms a heterodimer with the bHLH protein hes2, and weakly interacts with hey1/hrt1. First expressed weakly at stage 12 in primary neuronal precursors. At stages 18 and 21, strongly expressed in the cranial ganglions, with weaker expression remaining in the spinal cord. Later, strongly expressed at sites of neuronal differentiation, namely the eye, forebrain and cranial ganglions. Serine or threonine phosphorylation within the basic region may regulate neurogenic activity.