SECOND TYPE OF EDITING. “(ii) Co-opted adaptations of ribozymatic or ribozyme-like parts as remnants of former viral colonizers that now act as a great variety of regulatory elements in the present highly dynamic RNA world shortly after transcription out of stable DNA storage medium.”
http://jmcb.oxfordjournals.org/content/early/2011/03/31/jmcb.mjr005.full