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.