Transcription factor that binds to the immunoglobulin enhancer Mu-E5/KE5-motif. Involved in the initiation of neuronal differentiation. Activates transcription by binding to the E box (5'-CANNTG-3'). Binds to the E-box present in the somatostatin receptor 2 initiator element (SSTR2-INR) to activate transcription (By similarity). Interacts with the CCAAT displacement protein (CDP2) to bind the tyrosine hydroxylase enhancer. Efficient DNA binding requires dimerization with another bHLH protein. Forms homo- or heterooligomers with myogenin. Interacts with HIVEP2. Interacts with NEUROD2 (By similarity). Interacts with AGBL1 (By similarity).