EC - 1 ▁to ▁the ▁A po B ▁m R NA ▁down stream ▁of ▁the ▁edited ▁c yt id ine . ▁Other ▁auxili ary ▁factors ▁ ▁are ▁known ▁to ▁be ▁part ▁of ▁the ▁h olo enz yme . ▁Some ▁of ▁these ▁ ▁prote ins ▁have ▁been ▁identified . ▁these ▁are ▁C UG ▁binding ▁protein ▁ 2 ▁( C U GB P 2 ), ▁SY NC RI P ▁( gly c ine - argin ine - ty ros ine - rich ▁R NA ▁binding ▁protein , ▁G RY - R B P ), ▁heter ogen ous ▁nuclear ▁rib on uc le op rote in ▁( hn R NP )- C 1 , ▁A po B EC - 1 ▁binding ▁protein ▁( AB B P ) 1 , ▁A BB P 2 , ▁K H - type ▁sp lic ing ▁regul atory ▁binding ▁protein ▁( K SR P ), ▁B cl - 2 - associ ated ▁anth ogene ▁ 4 ▁( BA G 4 ), ▁and ▁auxili ary ▁factor ▁( AU X ) 2 4 0 . ▁All ▁these ▁prote ins ▁have ▁been ▁identified ▁using ▁detection ▁ass ays ▁and ▁have ▁all ▁been ▁demonstrated ▁to ▁interact ▁with ▁either ▁A po B EC - 1 , ▁A 1 CF , ▁or ▁A po B ▁R NA . ▁The ▁function ▁of ▁these ▁auxili ary ▁prote ins ▁in ▁the ▁editing ▁complex ▁are ▁unknown . ▁As ▁well ▁as ▁editing ▁A po B ▁m R NA , ▁the ▁A po B EC - 1 ▁ed its ome ▁also ▁ed its ▁the