Post-transcriptional changes in mRNA and tRNA of eukaryotic cells are important for proper protein synthesis. After transcription, pre-mRNA undergoes several modifications to become mature mRNA. These modifications include:
- Capping: The addition of a methylated guanine nucleotide to the 5' end of the mRNA molecule protects it from degradation and helps in ribosome binding during translation.
- Polyadenylation: The addition of a poly(A) tail to the 3' end of the mRNA molecule provides stability and enhances the efficiency of translation.
- Splicing: The removal of introns from the pre-mRNA and joining of exons to form a mature mRNA molecule. This process is mediated by the spliceosome, which recognizes specific sequences at the intron-exon boundaries.
In addition to mRNA modifications, tRNA molecules undergo post-transcriptional modifications, which include:
- Addition of modified bases: tRNA molecules contain several modified bases, which are important for maintaining proper folding and stability of the molecule.
- Splicing: Some tRNA molecules are synthesized as larger precursor molecules that require splicing to remove introns and generate mature tRNA molecules.
These post-transcriptional modifications are important for proper mRNA and tRNA function in translation, and any defects in these processes can lead to protein synthesis errors and various diseases.