Figure 1.

Schematic illustration of discreet RNA regulatory elements. The translation of an mRNA is regulated by diverse mechanisms that involve both structural and non-structural RNA elements, as well as interactions with RNA-binding proteins. IRESes are found in the 5′ UTR and promote cap-independent translation. Pseudoknots can be located in the 5′ UTR, the 3′ UTR, or the coding region, and their localization influences their effect on translation; for example, initiation, frameshifting and termination. 3′ UTR structural elements such as CREs, CITEs and SLs often function through long-range RNA interactions. The miRNA target sites are located in the 3′ UTR. The canonical mRNA features of the cap (m⁷G) and poly(A) are targets of several regulatory interactions. The RNA-binding protein-binding sites are shown as blue ovals, and the miRNA-binding site is shown as a brown rectangle. AUG, initiation codon; CITE, cap-independent translational enhancer; CRE, cis-acting replication element; IRES, internal ribosome entry site; m⁷G, 7-methyl-guanosine; miRNA, microRNA; mRNA, messenger RNA; ORF, open-reading frame; SL, stem loop; UTR, untranslated region.