Figure 3.

Functions of circular RNAs. (a) Ribosome. In the presence of internal ribosomal enter sites and a corresponding open reading frame, circRNAs can affect protein translation. (b) miRNA. CircRNAs can sponge the miRNAs to act as a cytoplasmic miRNA inventory. The scavenging of miRNAs removes the repression of target RNAs leading to an increase in their translation (in the case of mRNA) or activity (in case of lncRNA). (c) Protein. CircRNAs can act as a sponge for cytoplasmic proteins, retain certain transcription factors in the cytoplasm, or serve as a carrier for the transport of these molecules. (d) Substrate. CircRNAs can act as a scaffold for enzymes leading them to specific locations.