text: The existence of backsplicing was first suggested in 2012. This backsplicing explains the genesis of circular RNAs resulting from the exact junction between the 3 boundary of an exon with the 5 boundary of an exon located upstream. In these exonic circular RNAs, the junction is a classic 3-5link.
  The exclusion of intronic sequences during splicing can also leave traces, in the form of circular RNAs. In some cases, the intronic lariat is not destroyed and the circular part remains as a lariat-derived circRNA.In these lariat-derived circular RNAs, the junction is a 2-5link.