. ▁P ax ▁ 6 ▁is ▁a ▁master ▁reg ulator ▁of ▁eye ▁development , ▁such ▁that ▁the ▁gene ▁is ▁necessary ▁for ▁development ▁of ▁the ▁opt ic ▁ves icle ▁and ▁subsequent ▁eye ▁structures . ▁ ▁PO U ▁gen es ▁▁ ▁Prote ins ▁containing ▁a ▁PO U ▁region ▁consist ▁of ▁a ▁home od om ain ▁and ▁a ▁separate , ▁struct ur ally ▁hom olog ous ▁PO U ▁domain ▁that ▁contains ▁two ▁hel ix - turn - hel ix ▁mot ifs ▁and ▁also ▁bind s ▁DNA . ▁The ▁two ▁domains ▁are ▁linked ▁by ▁a ▁flexible ▁loop ▁that ▁is ▁long ▁enough ▁to ▁stretch ▁around ▁the ▁DNA ▁hel ix , ▁allowing ▁the ▁two ▁domains ▁to ▁bind ▁on ▁opposite ▁sides ▁of ▁the ▁target ▁DNA , ▁collect ively ▁covering ▁an ▁eight - base ▁segment ▁with ▁cons ensus ▁sequence ▁ 5 '- AT G CAA AT - 3 '. ▁The ▁individual ▁domains ▁of ▁PO U ▁prote ins ▁bind ▁DNA ▁only ▁weak ly , ▁but ▁have ▁strong ▁sequence - specific ▁aff inity ▁when ▁linked . ▁The ▁PO U ▁domain ▁itself ▁has ▁significant ▁struct ural ▁similarity ▁with ▁repr ess ors ▁expressed ▁in ▁b acter i oph ages , ▁particularly ▁lambda ▁ph age . ▁ ▁Plant ▁home obox ▁gen es ▁ ▁As ▁in ▁animals , ▁the ▁plant ▁home obox ▁gen es ▁code ▁for ▁the ▁typical ▁ 6 0 ▁am ino ▁acid ▁long ▁DNA - binding ▁home od om ain ▁or ▁in ▁case ▁of ▁the ▁T A LE ▁( three ▁am ino ▁acid ▁loop ▁extension ) ▁home obox ▁gen es ▁for ▁an ▁" at yp