Untranslated region

As untranslated region (abbreviated UTR, engl. Untranslated region ) is known in molecular biology, the edge regions of the mRNA, which does not code for proteins.

An mRNA encoding a protein which is synthesized in the translation. However, the mRNA also includes regions that are not translated. In eukaryotes, these regions are the 5 ' cap, 5' UTR, 3'- UTR, and the poly -A tail ( see illustration).

The 5 'UTR (that is, the 5' end of the mRNA ) extends from the transcription start point and before the translational start codon. The 3'UTR starts behind the translation stop codon and extends to the Polyadenylierungsstartpunkt ( at the 3 ' end of the mRNA ). The 5 ' UTR can be a hundred or more nucleotides in length, which 3' UTR even several thousand.

5'-UTR

The 5'- UTR (5 ' untranslated region, ie 5 - dot- UTR, Eng. Five prime untranslated region ), also known as a leader sequence, a certain part of the mRNA or the DNA coding for this mRNA. It begins at the transcriptional start site ( position 1 ) and ends before the translation of the coding region. Normally, this includes a ribosomal binding site in bacteria known as the Shine-Dalgarno sequence.

Various regulatory sequences can be present in the 5 ' UTR:

  • Binding sites for proteins which can affect the stability of the mRNA or its translation.
  • Regulatory elements which operate independently of proteins, such as riboswitches.
  • Sequences which initiate the initiation of translation.

3'- UTR

The 3' -UTR (3 ' untranslated region, ie 3- dot- UTR, Eng. Three prime untranslated region ) is a region of the mRNA, which adjoins the coding region. It starts after the translation stop codon and extends to the Polyadenylierungsstartpunkt.

Different regulatory sequences can be located in the 3'- UTR:

  • A polyadenylation signal sequence, which marks the termination of the transcript about 30 base pairs downstream of the signal followed by several hundreds of adenine residues.
  • Binding sites for proteins that affect the stability or transport of mRNA.
  • Binding sites for miRNAs.
Digital Object Identifier Medical Subject Headings
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