Transcriptional regulator. Involved in the initiation of neuronal differentiation. Activates transcription by binding to the E box (5'-CANNTG-3'). Efficient DNA binding requires dimerization with another bHLH protein. Forms homo- or heterooligomers with myogenin, E12 and ITF2 proteins. Interacts with PTF1A. Interacts with RUNX1T1. Interacts with NEUROD2 (By similarity). Interacts with BHLHA9.