Figure 1.

Biosynthesis of circRNAs. Various mechanisms are involved for generating different circRNAs types. A. Intron-pairing-driven circularization, involves the complementarity between the introns on either side of pre-mRNA. B. Lariat-driven circularization, involves formation of exonic circRNAs or EIciRNAs that does/does not involve intron removal with skipping of the exon along with RNA folding. C. Binding to the introns at specific sequences to influence circRNA biogenesis. D. CircRNA biogenesis involves the formation of lariat between conserved motifs at various combinations located upstream/downstream of introns. E. Formation of circular RNA (triRNA) by splicing of the pre-tRNA into two parts, with a 3’-5’ phosphodiester bond bound in one. F. Canonical pre-mRNA splicing and mRNA biogenesis.