Transcriptional repressor. Represses transcription from both N box- and E box-containing promoters. May with HES1, cooperatively regulate somite formation in the presomitic mesoderm (PSM). May function as a segmentation clock, which is essential for coordinated somite segmentation (By similarity). Transcription repression requires formation of a complex with a corepressor protein of the Groucho/TLE family. Has a particular type of basic domain which includes a helix-interrupting proline. The C-terminal WRPW motif is a transcriptional repression motif which is necessary for interaction with Groucho/TLE family members, transcriptional corepressors recruited to specific target DNA by Hairy-related proteins. The disease is caused by variants affecting the gene represented in this entry.