File:Fgene-10-00006-g001.jpg

English: General modes and determinants of 3′UTR in post-transcriptional regulation. (A) Schematic illustration of the distinctive features of an eukaryotic mRNA. The 5′-terminal cap structure interacts with the 3′-terminal poly(A) tail of an mRNA through associated eIF4F and PABP. The coding sequence (CDS) is flanked by 5′- and 3′UTR, which harbors cis-regulatory sequences (marked in red) and provides a binding platform for trans-acting factors (green). (B) Translational repression mechanisms. (i) Competition/interference with cap-binding complex, eIF4F (ii) Inhibition of ribosomal subunit joining (iii) Inhibition of translation elongation. (C) Deadenylation and decapping. Recruitment of the CCR4-NOT deadenylase complex by trans-acting factors catalyzes the deadenylation of the mRNA target. This is often followed by the removal of the 5′-terminal cap structure by the decapping factors (DCP1-DCP2), and the associated co-factors. (D) mRNA decay. mRNAs that are deadenylated and decapped are rapidly degraded by either 5′- > 3′ exonuclease (XRN1) or 3′- > 5′ exonuclease (exosome). (E) RNA localization. Translationally repressed mRNAs are transported along the cytoskeleton to which it is tethered by RBPs and motor proteins. Upon reaching its destination, the mRNA is anchored, and its translation is de-repressed.