Acts as a transcriptional corepressor. Negative regulator of the transcriptional activity of tbx1 that plays a key role in pharyngeal development. Plays a role in the formation of the anteroposterior (AP) axis during embryonic development; required to establish the posterolateral border of the pre-placodal ectoderm (PPE) acting downstream of the retinoic acid receptor (RAR) signaling (By similarity). Interacts with tbx1 and tle4/grg4. 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.