Transcriptional repressor of genes that require a bHLH protein for their transcription. May serve as a transcriptional regulator of the Achaete-scute complex (AS-C) genes. Belongs to notch signaling pathway and depends on Su(H) for transcriptional activation. Transcription repression requires formation of a complex with a corepressor protein (Groucho). The RNA is supplied maternally, and later on, expression is ubiquitous during all stages of embryonic development. 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, a transcriptional corepressor recruited to specific target DNA by Hairy-related proteins.