mRNA Untranslated Regions (UTRs)

Abstract

Eukaryotic messenger ribonucleic acids (mRNAs) possess a tripartite structure that comprises a 5′ untranslated region, a coding region made up of the amino acid coding triplet codons and a 3′ untranslated region. During nuclear maturation of primary transcripts, both ends of mRNA are post‐transcriptionally modified through the addition of a 7‐methyl‐guanosine cap structure at the 5′ end and a polyadenosine tail at the 3′ end. Untranslated regions are involved in the post‐transcriptional regulation of gene expression by modulating mRNA stability, nucleo‐cytoplasm transport, subcellular localisation and translation efficiency thus allowing a fine control of the protein product. This regulatory activity is mediated by cis‐acting oligonucleotide elements that interact with binding proteins and noncoding RNAs through a combination of primary and secondary structures.

Key Concepts:

  • UTRs are involved in the post‐transcriptional regulation of gene expression.

  • UTRs regulate mRNA stability, nucleo‐cytoplasm transport, subcellular localisation and translation efficiency.

  • Alternative splicing can result in mRNAs encoding the same protein under the control of different UTRs.

Keywords: post‐transcriptional regulation; RNA‐binding proteins; translation; mRNA stability; mRNA localisation

Figure 1.

Examples of untranslated (UTR) elements with known secondary structure: (a) human basic fibroblast growth factor (GenBank accession number J04513) IRES element; (b) IRE structure of human transferrin (GenBank accession number M11507); (c) selenocysteine insertion sequence from human SelZ mRNA (GenBank accession number AF166127). Nucleotides that are conserved among the same elements from different transcripts are highlighted by filled circles.

Figure 2.

Structure of a eukaryotic mRNA that depicts some post‐transcriptional regulatory elements. Factors influencing message stability include uAUGs, uORFs, antisense noncoding RNAs (ncRNAs) and elements embedded in both the 5′ and 3′ UTRs. Modulation of translation may be mediated by the secondary structure of the 5′ UTR, uAUGs or uORFs, as well as by protein‐mediated poly(A) tail interaction with the 7mG cap. Subcellular localisation of mRNA is often mediated by miRNA elements located in the 3′ UTR.

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Further Reading

Conne B, Stutz A and Vassalli JD (2000) The 3′ untranslated region of messenger RNA: a molecular ‘hotspot’ for pathology? Nature Medicine 6: 637–641.

Jansen RP (2001) mRNA localization: message on the move. Nature Reviews Molecular Cell Biology 2: 247–256.

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van der Velden AW and Thomas AA (1999) The role of the 5′ untranslated region of an mRNA in translation regulation during development. International Journal of Biochemistry and Cell Biology 31: 87–106.

Wilusz CJ, Wormington M and Peltz SW (2001) The cap‐to‐tail guide to mRNA turnover. Nature Reviews Molecular Cell Biology 2: 237–246.

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How to Cite close
Mignone, Flavio, and Pesole, Graziano(Aug 2011) mRNA Untranslated Regions (UTRs). In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1002/9780470015902.a0005009.pub2]