Transcriptional repressor of genes that require a bHLH protein for their transcription. Plays an important role as neurogenesis negative regulator (By similarity). Transcription repression requires formation of a complex with a corepressor protein of the Groucho/TLE family. Expressed predominantly in embryonic neural lineage cells. Has a particular type of basic domain (presence of a helix-interrupting proline) that binds to the N-box (CACNAG), rather than the canonical E-box (CANNTG). The C-terminal WRPW motif is a transcriptional repression domain necessary for the interaction with Groucho/TLE family members, transcriptional corepressors recruited to specific target DNA by Hairy-related proteins.