May act as a specific coactivator for the mammalian TEFs. May play a role in the development of skeletal muscles. Interacts with TEFs. Binds to TEAD1/TEF1. Skeletal muscle specific. Expressed in the somitic myotome from 8.75 dpc mouse embryos onwards and later on in skeletal muscle but not in the heart. Additional expression domains during development are detected in the pharyngeal pouches and clefts starting at 8.0 dpc as well as in the cranial pharynx and in Rathkes pouch. Belongs to the vestigial family.