FIG. 5.

Effects that A-to-I RNA editing may exert on gene expression and function. Adenosine (A) deamination to inosine (I) in duplex RNA structures catalyzed by ADARs substitutes an I for an A in an RNA sequence. Because I is recognized as G, A-to-I editing may effect gene expression and function in a number of ways that include mRNA translation by changing codons and hence the amino acid sequence of expressed proteins; pre-mRNA splicing by changing a conserved A in splice site recognition sequences; RNA stability by altering sequences involved in nuclease recognition; RNA virus genome stability by changing template and thus product sequences during viral RNA replication; and, RNA-structure-dependent activities such as microRNA production or targeting or protein-RNA interactions (adapted from Samuel 2003 with permission).