Long RNA hairpins that contain inosine are present in Caenorhabditis elegans poly(A)(+) RNA

Adenosine deaminases that act on RNA (ADARs) are RNA-editing enzymes that c onvert adenosine to inosine within double-stranded RNA. In the 12 years sin ce the discovery of ADARs only a few natural substrates have been identifie d. These substrates were found by chance, when genomically encoded adenosin es were identified as guanosines in cDNAs. To advance our understanding of the biological roles of ADARs, we developed a method for systematically ide ntifying ADAR substrates. In our first application of the method, we identi fied five additional substrates in Caenorhabditis elegans. Four of those su bstrates are mRNAs edited in untranslated regions, and one is a noncoding R NA edited throughout its length. The edited regions are predicted to form l ong hairpin structures, and one of the RNAs encodes POP-1, a protein involv ed in cell fate decisions.