Transcriptional repressor of a subset of early mesodermal genes including myod1 and t/bra. Binds DNA on N-box motifs: 5'-CACNAG-3'. Acts as a negative regulator of myogenesis, mediating Notch signaling to repress expression of myod1. Transcription repression requires formation of a complex with a corepressor protein of the Groucho/TLE family (By similarity). Interacts with the bHLH protein hes2, and binds DNA in the form of a heterodimer with the bHLH protein hey1/hrt1. Interacts with the bHLH protein hes6; this interaction may inhibit the transcriptional repressor activity. Starting from late neurula stage, weakly expressed in midline neural cells, where expression is restricted to the superficial layer of the prospective floorplate. Expressed in the posterior somitic mesoderm (PSM) at tailbud stage. During early tailbud stages, broadly expressed within the pronephric mesoderm both around and inside the developing pronephros. During late tailbud to early tadpole stages, expressed more ventrally in the pronephros, and although initially expressed in both the lateral and medial layers, by these later stages expression is predominantly in the lateral layer. Pronephric expression is no longer detectable in late tadpoles (stage 35). Expression begins soon after the mid-blastula transition. 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 bHLH, as well as cooperation between the central Orange domain and the C-terminal WRPW motif, is required for transcriptional repressor activity. 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.