RNA editing is a molecular process through which some cells can make discrete changes to specific nucleotide sequences within a RNA molecule after it has been generated by RNA polymerase. RNA editing is relatively rare, and common forms of RNA processing (e.g. splicing, 5'-capping and 3'-polyadenylation) are not usually included as editing. Editing events may include the insertion, deletion, and base substitution of nucleotides within the edited RNA molecule.
RNA editing has been observed in some tRNA, rRNA, mRNA and miRNA molecules of eukaryotes and their viruses, but has not been seen in prokaryotes. RNA editing occurs in the cell nucleus and cytosol, as well as within mitochondria and plastids. In vertebrates, editing is rare and usually consists of a small number of changes to the sequence of affected molecules. In other organisms, extensive editing (pan-editing) can occur; in some cases the majority of nucleotides in a mRNA sequence may result from editing.
RNA-editing processes show great molecular diversity, and some appear to be evolutionarily recent acquisitions that arose independently. The diversity of RNA editing phenomena includes nucleobase modifications such as cytidine (C) to uridine (U) and adenosine (A) to inosine (I) deaminations, as well as non-templated nucleotide additions and insertions. RNA editing in mRNAs effectively alters the amino acid sequence of the encoded protein so that it differs from that predicted by the genomic DNA sequence.
Read more about RNA Editing: Editing By Insertion or Deletion, RNA Editing in Plant Mitochondria and Plastids, RNA Editing in Viruses, Origin and Evolution of RNA Editing, RNA Editing May Be Involved in RNA Degradation
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“In this century the writer has carried on a conversation with madness. We might almost say of the twentieth-century writer that he aspires to madness. Some have made it, of course, and they hold special places in our regard. To a writer, madness is a final distillation of self, a final editing down. It’s the drowning out of false voices.”
—Don Delillo (b. 1926)