fig1

Figure 1. Biosynthetic mechanisms for circRNAs. (A) Lariat-driven circularization: lariat causes exons or introns that were originally far apart to come closer; (B) Intron pairing-driven circularization: complementary sequences in introns promote circRNA circularization by base pairing to bring the 3' splice acceptor site and the 5' splice donor site closer together in spatial conformation; (C) RBP-dependent circularization: RBPs bind to intronic sequences or specific motifs within flanking introns near the splice site and indirectly bridge the distance between upstream and downstream exons. RBP: RNA binding protein.