Post-Transcriptional Modification Turns pre-mRNA Into Mature mRNA
- In eukaryotic cells, the initial RNA transcript, called pre-mRNA, undergoes several modifications to become mature mRNA.
- These modifications occur in the nucleus to ensure the mRNA is stable, functional, and ready for translation in the cytoplasm.
Post-transcriptional modification is unique to eukaryotes.
Key Steps in Post-Transcriptional Modification
- Removal of Introns and Splicing of Exons
- Eukaryotic genes contain exons (coding regions) and introns (non-coding regions).
- Introns are removed from the pre-mRNA by a complex called the spliceosome.
- The remaining exons are joined together (spliced) to form a continuous coding sequence.
- This produces mature mRNA containing only the coding regions.
- Addition of a 5' Cap
- A modified guanine nucleotide is added to the 5' end of the pre-mRNA.
- The 5' cap:
- Protects the mRNA from degradation by enzymes.
- Facilitates ribosome binding during translation.
