Transcriptional regulator. Involved in the initiation of neuronal differentiation. Activates transcription by binding to the E box (5'-CANNTG-3'). Participates in the control of inducible RP4 gene expression in salivary cells (By similarity). Binds to the RIPE3 element of the insulin II promoter. Efficient DNA binding requires dimerization with another bHLH protein. Forms homo- or heterooligomers with myogenin, E12 and ITF2 proteins. Interacts with NEUROD2. Interacts with PTF1A. Interacts with RUNX1T1 (By similarity). Interacts with BHLHA9.