4. Maturation of the eukaryotic pre-mRNA transcript

Figure 17

Figure 17

4.2 Addition of the poly-A tail in 3'

Transcription terminates upon recognition of the transcription termination sequence.

Nucleotides A are added at the 3’ of the pre-mRNA.

Approximately 200 A are added by a poly A polymerase.

The functions of the poly-A tail are to:

  • Protect the 3’ end of the mRNA against degradations
  • Allow for the exit from the nucleus.