▁patterns ▁of ▁an atom ical ▁development ▁( m orph ogen esis ) ▁in ▁animals , ▁fung i , ▁plants , ▁and ▁numerous ▁single ▁cell ▁e uk ary otes . ▁Home obox ▁gen es ▁encode ▁home od om ain ▁protein ▁products ▁that ▁are ▁trans cription ▁factors ▁sharing ▁a ▁characteristic ▁protein ▁fol d ▁structure ▁that ▁bind s ▁DNA ▁to ▁reg ulate ▁expression ▁of ▁target ▁gen es . ▁ ▁Home od om ain ▁prote ins ▁reg ulate ▁gene ▁expression ▁and ▁cell ▁different iation ▁during ▁early ▁emb ry onic ▁development , ▁thus ▁mut ations ▁in ▁home obox ▁gen es ▁can ▁cause ▁development al ▁dis orders . ▁▁ ▁Home osis ▁is ▁a ▁term ▁co ined ▁by ▁William ▁B ates on ▁to ▁describe ▁the ▁out right ▁replacement ▁of ▁a ▁discrete ▁body ▁part ▁with ▁another ▁body ▁part , ▁e . g . ▁anten nap edia — rep lacement ▁of ▁the ▁anten na ▁on ▁the ▁head ▁of ▁a ▁fruit ▁fly ▁with ▁legs . ▁The ▁" home o - " ▁prefix ▁in ▁the ▁words ▁" home obox " ▁and ▁" home od om ain " ▁st ems ▁from ▁this ▁mut ational ▁phen ot ype , ▁which ▁is ▁frequently ▁observed ▁when ▁these ▁gen es ▁are ▁mut ated ▁in ▁animals . ▁The ▁home obox ▁domain ▁was ▁first ▁identified ▁in ▁a ▁number ▁of ▁D ros oph ila ▁home otic ▁and ▁segment ation ▁prote ins , ▁but ▁is ▁now ▁known ▁to ▁be ▁well - con ser ved ▁in ▁many ▁other ▁animals , ▁including ▁verte br ates . ▁ ▁Disc overy ▁▁ ▁The ▁existence ▁of ▁home obox