Genes of the Compass (Cmp) gene family encode a protein with a Compass domain and two homeodomains, but no Cut domain. Although they lack the Cut domain, but are placed in the CUT class because they share the Compass domain with the Satb gene family. Thus far, Satb genes have only been found in vertebrates, and Cmp genes only in invertebrates. Bürglin and Cassata (2002) have proposed that the vertebrate Satb gene family evolved from the invertebrate Cmp gene family. Amphioxus has one Cmp family gene, and Drosophila has one (Dve, defective proventriculus).|
Bürglin TR, Cassata G (2002) Int J Dev Biol 46:115-123.