5′‐UTRs and Regulation

Flavio Mignone, University of Milan, Milan, Italy
Graziano Pesole, University of Bari, Bari, Italy

Published online: September 2007

DOI: 10.1002/9780470015902.a0005010.pub2

The 5¢ untranslated region consists of the leading part of a cellular messenger ribonucleic acid (mRNA) from the 5¢ end to the translation start codon AUG. Precursor mRNA is posttranscriptionally modified by the removal of introns and by the addition at the 5¢ end of a 7-methyl-guanylate cap structure, which has a crucial role in translation initiation and in regulating transcript stability. 5¢-UTRs as well as 3¢-UTRs, are deeply involved in regulation of gene expression through specific motifs that can affect mRNA stability, subcellular localization, nuclear export, tissue specificity and efficiency of translation.

Keywords: translation initiation; mRNA stability; uAUG; uORF; internal ribosome entry site

Figure 1. mRNAs with alternative 5¢-UTRs can be generated either by the use of alternative promoters, which results in different transcription start sites (TSS1 and TSS2), or by alternative spicing events. In this way, alternative 5¢-UTRs corresponding to the same gene may contain different combinations of regulatory elements, as shown here. CDS: coding sequence; mG7: 7-methyl-guanylate; IRES: internal ribosome entry site; sAUG: start AUG; uAUG: upstream AUG; uORF: upstream open reading frame.
Figure 2. Translation initiation regulation. (a) Canonical scanning model; (b) ribosome stalling; (c) inefficient (top) and efficient (bottom) reinitiation, depending on the distance between the uORF and the sAUG; (d) regulation by uORF-encoded peptide; (e) detachment of the ribosome mediated by an uORF stop codon; (f) IRES-mediated initiation; (g) inhibition of secondary structure; (h) in-frame or out-of-frame translation starting from an uAUG.
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Related Sub-Topics:

Protein Structure | Nucleic Acid Structure | Translation and Protein synthesis | Protein Folding, Evolution and Degradation | Translational Regulation | RNA Structure and Function | Noncoding RNA | Posttranscriptional Modification | Cell Signalling | Proteins: Structure, Function, Metabolism | Enzymes: Structure and Action Mechanism | Nucleic Acids: Structure, Function, Metabolism
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Article Title: 5′‐UTRs and Regulation
 
How to Cite close
Mignone, Flavio, and Pesole, Graziano(Sep 2007) 5′‐UTRs and Regulation. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1002/9780470015902.a0005010.pub2]