| CUGBP 2 modulates C to U editing of apolipoprotein B mRNA by interacting with apobec 1 and ACF , the apobec 1 complementation factor . ^^^ CUGBP 2 and ACF co fractionate in bovine liver S 100 extracts , and addition of recombinant apobec 1 leads to assembly of a holoenzyme . ^^^ However , addition of recombinant CUGBP 2 to a reconstituted system demonstrated a dose dependent inhibition of C to U RNA editing , which was rescued with either apobec 1 or ACF . ^^^ Antisense CUGBP 2 knockout increased endogenous apoB RNA editing , whereas antisense knockout of either apobec 1 or ACF expression eliminated apoB RNA editing , establishing the absolute requirement of these components of the core enzyme . ^^^ These data suggest that CUGBP 2 plays a role in apoB mRNA editing by forming a regulatory complex with the three components of the minimal editing enzyme , apobec 1 , ACF , and apoB RNA . . ^^^ |