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. Interacts with tbx1 and tle4/grg4. At neurula stage, expressed in the region close to the heart mesoderm. At the tailbud stage, expressed in the pharyngeal region. Maternally expressed. Ubiquitously expressed until stage 16. Expressed in the pre-placodal ectoderm domain at stage 18. Expressed in the epibranchial placodes of the tailbud embryos. Expressed in the pronephros. Up-regulated by retinoc acid (RA) in the pre-placodal ectoderm (PPE) during development. 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.