The portions of a messenger RNA that are not translated into amino acid sequence. The 5′ leader sequence (5′ UTR) may be more than 100 nucleotides long and contains a ribosome binding site. The 3′ UTR, which may be several kilobases long, presumably has some function, although that function is unclear, and is terminated by the poly-A tail. The 5′ end also has a cap of a few bases.
Subjects: Medicine and Health.