What is the consequence of 3' polyadenylation in eukaryotic mRNA processing?

• A. It signals transcription termination
• B. It initiates splicing
• C. It stabilizes the transcript and aids export to the cytoplasm for translation
• D. It encodes start codon

Answer: (C)

Adding a poly(A) tail at the 3' end of eukaryotic mRNA serves to stabilize the transcript and help it reach the cytoplasm for translation. The poly(A) tail binds specialized proteins that protect the mRNA from exonucleases, increasing its lifespan. Those same proteins also interact with translation initiation factors and the cap-binding complex, promoting efficient initiation and often helping the mRNA form a loop that enhances ribosome recycling. The tail’s role is in stability, export, and translation efficiency, not in signaling transcription termination, initiating splicing, or encoding the start codon—the latter is set by the coding sequence itself.