Chromatin-binding factor that repress Notch signaling in the absence of Notch intracellular domain by acting as a CBF1 corepressor. Binds to the HEY promoter and might assist, along with NCOR2, RBPJ-mediated repression. Can suppress ATXN1 cytotoxicity in spinocerebellar ataxia type 1 (SCA1) (By similarity).