Transcriptional repressor. Binds DNA on N-box motifs: 5'-CACNAG-3'. Promotes floor plate development and prechordal plate development. Required for lens development as early as the stage of lens field formation, partly through regulation of gene expression of the cell cycle inhibitor cdknx/p27(xic1). Required for formation of the neural crest downstream of multiple signaling pathways, and acts at the neural plate border via both DNA-binding dependent and independent mechanisms. Also acts via repressor-dependent and repressor-independent mechanisms in early gastrulae to establish the prospective anterior prechordal mesoderm identity in the Spemann organizer; induces specific genes independently from direct transcriptional regulation, and represses the genes specific for neighboring tissues through direct transcriptional repression. Modulates lateral inhibition during notch signaling and regulates the cell context dependent effects of notch (which can have inhibitory, permissive or enhancing roles in muscle or neural differentiation). Inhibits myogenesis (By similarity). Transcription repression requires formation of a complex with a corepressor protein of the Groucho/TLE family. Interacts with the bHLH protein hes6; this interaction may inhibit the transcriptional repressor activity. Binds DNA in the form of a heterodimer with the bHLH protein hey1/hrt1. Interacts (via Orange domain) with id3 (via HLH domain) (By similarity). 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. The WPRW motif is also required for the inductive function, independent of transcription regulation activity (By similarity).