Messenger RNA (mRNA): The Link Between DNA and Protein

Messenger RNA (mRNA) provides a link between nucleic acids and proteins. Prokaryotic mRNA is polycistronic and contains a Shine–Dalgarno sequence for ribosome binding. Eukaryotic mRNAs are more complex and generally contain a cap and poly(A) tail. The 5′ UTR contains regulatory features, such as upstream open reading frames, Kozak consensus sequence, stem loop structures and internal ribosome entry sites (IRES). The 3′ UTR also contains regulatory sites: AU-rich elements, stem loops and microRNA response elements as well as a poly(A) tail. Mutations in either the 5′ or 3′ UTR have been associated with human diseases.