Acts as a transcriptional corepressor. Negative regulator of the transcriptional activity of TBX1. Plays a role in the development of the pharyngeal apparatus and derivatives (By similarity). Interacts with TBX1. Expressed at a low level in fetal kidney and fetal brain. The Ripply homology domain and the WRPW motif are both necessary for its transcriptional corepressor activity on the transcription activator TBX1. The WRPW motif is required for binding to tle/groucho proteins. Belongs to the ripply family.