Transcription factor that plays a key role in neuronal differentiation: acts as a pioneer transcription factor, accessing closed chromatin to allow other factors to bind and activate neural pathways (PubMed:10648228). Directly binds the E box motif (5'-CANNTG-3') on promoters and promotes transcription of neuronal genes. The combination of three transcription factors, ASCL1, POU3F2/BRN2 and MYT1L, is sufficient to reprogram fibroblasts and other somatic cells into induced neuronal (iN) cells in vitro. Plays a role at early stages of development of specific neural lineages in most regions of the CNS, and of several lineages in the PNS. Essential for the generation of olfactory and autonomic neurons. Acts synergistically with FOXN4 to specify the identity of V2b neurons rather than V2a from bipotential p2 progenitors during spinal cord neurogenesis, probably through DLL4-NOTCH signaling activation. Involved in the regulation of neuroendocrine cell development in the glandular stomach (By similarity). Efficient DNA binding requires dimerization with another bHLH protein. Forms a heterodimer with TCF3. Developing CNS and PNS at embryonic and postnatal stages. It is first observed after neurulation, in 10.5 day old (E10.5) rat embryos, and is restricted to subsets of neuroepithelial cells in the spinal cord and the brain, between E10.5 and E13.5. In the periphery, its expression is restricted to some lineages of neural crest-derived cells, namely in sympathetic and enteric neural precursors. In the PNS its expression is extinguished at or before differentiation.