ners ▁binding ▁to ▁the ▁arm ad illo ▁domain ▁▁ ▁As ▁sketch ed ▁above , ▁the ▁AR M ▁domain ▁of ▁beta - c aten in ▁acts ▁as ▁a ▁platform ▁to ▁which ▁specific ▁linear ▁mot ifs ▁may ▁bind . ▁Loc ated ▁in ▁struct ur ally ▁diverse ▁partners , ▁the ▁ β - c aten in ▁binding ▁mot ifs ▁are ▁typically ▁dis ordered ▁on ▁their ▁own , ▁and ▁typically ▁adopt ▁a ▁rig id ▁structure ▁upon ▁AR M ▁domain ▁eng agement ▁– ▁as ▁seen ▁for ▁short ▁linear ▁mot ifs . ▁However , ▁ β - c aten in ▁interact ing ▁mot ifs ▁also ▁have ▁a ▁number ▁of ▁peculiar ▁characteristics . ▁First , ▁they ▁might ▁reach ▁or ▁even ▁sur pass ▁the ▁length ▁of ▁ 3 0 ▁am ino ▁ac ids ▁in ▁length , ▁and ▁contact ▁the ▁AR M ▁domain ▁on ▁an ▁excess ively ▁large ▁surface ▁area . ▁Another ▁unusual ▁feature ▁of ▁these ▁mot ifs ▁is ▁their ▁frequently ▁high ▁degree ▁of ▁ph osph ory lation . ▁Such ▁Ser / T hr ▁ph osph ory lation ▁events ▁greatly ▁enh ance ▁the ▁binding ▁of ▁many ▁ β - c aten in ▁associ ating ▁mot ifs ▁to ▁the ▁AR M ▁domain . ▁ ▁The ▁structure ▁of ▁beta - c aten in ▁in ▁complex ▁with ▁the ▁c aten in ▁binding ▁domain ▁of ▁the ▁trans cription al ▁trans activ ation ▁partner ▁T CF ▁provided ▁the ▁initial ▁struct ural ▁road map ▁of ▁how ▁many ▁binding ▁partners ▁of ▁beta - c aten in ▁may ▁form ▁interactions . ▁ ▁This ▁structure ▁demonstrated ▁how ▁the ▁otherwise ▁dis ordered