▁m R NA ▁of ▁N F 1 . ▁m R NA ▁editing ▁of ▁A po B ▁m R NA ▁is ▁the ▁best ▁defined ▁example ▁of ▁this ▁type ▁of ▁C ▁to ▁U ▁ ▁R NA ▁editing ▁in ▁humans . ▁ ▁Location ▁Despite ▁being ▁a ▁ 1 4 , 0 0 0 ▁resid ue ▁long ▁trans cript , ▁a ▁single ▁c yt id ine ▁is ▁target ed ▁for ▁editing . ▁Within ▁the ▁A po B ▁m R NA ▁a ▁sequence ▁consisting ▁of ▁ 2 6 ▁nucle ot ides ▁necessary ▁for ▁editing ▁is ▁found . ▁This ▁is ▁known ▁as ▁the ▁editing ▁mot if . ▁These ▁nucle ot ides ▁( 6 6 6 2 – 6 6 8 7 ) ▁were ▁determined ▁to ▁be ▁essential ▁by ▁site ▁specific ▁mut agen esis ▁experiments . ▁An ▁ 1 1 ▁nucle ot ide ▁portion ▁of ▁this ▁sequence ▁ 4 – 5 ▁nucle ot ides ▁down stream ▁from ▁the ▁editing ▁site ▁is ▁an ▁important ▁region ▁known ▁as ▁the ▁mo oring ▁sequence . ▁A ▁region ▁called ▁the ▁spac er ▁element ▁is ▁found ▁ 2 – 8 ▁nucle ot ides ▁between ▁the ▁edited ▁nucle os ide ▁and ▁this ▁mo oring ▁sequence . ▁There ▁is ▁also ▁a ▁regul atory ▁sequence ▁ 3 ′ ▁to ▁the ▁editing ▁site . ▁The ▁active ▁site ▁of ▁A po B EC - 1 , ▁the ▁catal yt ic ▁component ▁of ▁the ▁editing ▁h olo enz yme ▁is ▁thought ▁to ▁bind ▁to ▁an ▁A U ▁rich ▁region ▁of ▁the ▁mo oring ▁sequence ▁with ▁the ▁aid ▁of ▁A CF ▁in ▁binding