Three prime untranslated region

The three prime untranslated region (3' UTR) is a particular section of messenger RNA (mRNA). It follows the coding region.

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An mRNA molecule codes for a protein through translation. The mRNA also contains regions that are not translated. In eukaryotes these regions are the cap, 5' untranslated region, 3' untranslated region, and polyA tail (see diagram).

In prokaryotes mRNA structures have some differences (see mRNA) as do histone mRNAs. However, both have 3' UTRs.

Several regulatory sequences are found in the 3' UTR:

• A polyadenylation signal, usually AAUAAA, or a slight variant. This marks the site of cleavage of the transcript approximately 30 base pairs past the signal, followed by the addition of several hundred adenine residues (poly-A tail).
• Binding sites for proteins, that may affect the mRNA's stability or location in the cell, like SECIS elements (which direct the ribosome to translate the codon UGA as selenocysteines rather than as a stop codon), or AU rich elements (AREs), stretches consisting of mainly adenine and uridine nucleotides (which can either stabilize or destabilize the mRNA depending on the protein bound to it).
• Binding sites for miRNAs, a type of RNAi.

References

• Mazumder B, Seshadri V, Fox PL (2003). "Translational control by the 3'-UTR: the ends specify the means". Trends Biochem. Sci. 28 (2): 91-8. doi:10.1016/S0968-0004(03)00002-1. PMID 12575997.