Regulation of inosine deposition. ADAR2 and ADAR1p110 act mainly in the nucleus on pre-mRNA. Recoding events, frequently introduced by ADAR2, are often defined by double-stranded structures formed between introns and exons. Consequently, the splicing machinery and the editing machinery compete for similar regions in RNA and may control each other, as seen in the editing of Gria2 or Flna. Conversely, ADAR can introduce splice sites, therefore introducing novel splice variants. In the cytoplasm, ADAR1p150 is responsible for the hyper-editing of many repeat-derived, structured RNA segments. At present, we do not know whether editing marks are introduced stochastically, on different molecules, or in a coordinated manner along individual RNAs.
