 The type of RNA editing that is most prevalent in higher eukaryotes converts adenosine nucleotides into inosine in dsRNAs via the enzyme adenosine deaminase ( ADAR ) . It was originally proposed in 2000 that the RNAi and A → I RNA editing pathways might compete for a common dsRNA substrate . Some pre @-@ miRNAs do undergo A → I RNA editing and this mechanism may regulate the processing and expression of mature miRNAs . Furthermore , at least one mammalian ADAR can sequester siRNAs from RNAi pathway components . Further support for this model comes from studies on ADAR @-@ null C. elegans strains indicating that A → I RNA editing may counteract RNAi silencing of endogenous genes and transgenes . 
