Figure 1. Elements that influence translation of mRNA.

The m⁷GpppN cap structure at the 5′ end of the mRNA, and the poly(A) tail ((A)_n in the figure) at the 3′ end, are canonical motifs that strongly promote translation initiation. Secondary structures, such as hairpins, block translation. Internal ribosome entry sequences (IRESs) mediate cap-independent translation. Upstream open reading frames (uORFs) normally function as negative regulators by reducing translation from the main ORF. Green ovals symbolize binding sites for proteins and/or RNA regulators, which usually inhibit, but occasionally promote, translation.