APOBEC1 complementation factor (A1CF or ACF) and APOBEC1 (an RNA-binding cytidine deaminase) form the apolipoprotein B (apoB) mRNA editing enzyme complex, which is responsible for the postranscriptional editing of a CAA codon for Gln to a UAA codon for stop in apoB mRNA [, ]. APOBEC1 alone induces nonsense-mediated decay (NMD), while the APOBEC1-ACF complex edits and remains associated with the edited RNA to protect it from NMD []. ACF has been shown to bind with high affinity to single-stranded but not double-stranded apoB mRNA [].
