4. Maturation of the eukaryotic pre-mRNA transcript

Figure 16: During transcription, a cap is added at the 5’ end of the RNA strand.

Figure 16: During transcription, a cap is added at the 5’ end of the RNA strand.

Nearly all different types of RNA are modified prior to being used (through maturation or post-transcriptional modifications).

Only the modifications of eukaryotic mRNA are described here.

4.1 Cap addition in 5'

Cap addition is carried out at the beginning of transcription. Addition of a supplementary specific nucleotide in 5’ of the 1st nucleotide of the newly transcribed RNA.

The functions of capping are to :

  • Identify mRNA among other types of RNA
  • Protect mRNA against degradations
  • Facilitate the initiation of translation