Acts as a transcriptional activator. Plays a role as a differentiation factor during neurogenesis. Required for the conversion of cells within the neural plate and ventral ectoderm into differentiated neurons. Promotes the differentiation of late-born retinal amacrine cells, but not early-born retinal ganglion cells. Its function is inhibited at early stages of retinal cells differentiation. 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. Expressed in differentiating neurons of both the central and peripheral nervous systems. Expressed in the neural plate at stage 14 and expression continues throughout embryonic development. Expressed in the developing retina. Phosphorylation on Ser-266 and Ser-274 reduces protein accumulation and inhibits ectopic neurogenic activity.