Fig. 4
From: Deep Insights in Circular RNAs: from biogenesis to therapeutics
Different circRNAs have different back splicing mechanisms: Exonic circRNAs have cycling sequencing such as the ALU sequence, on the two sides, which binds to each other complimentarily. After that they are spliced by the spliceosome, which consists of U2 and U6. Intronic circRNA form a loop through the combination of upstream introns of the GU rich sequence and the downstream C rich sequence, and they are spliced by spliceosome