What function does the Poly A tail serve in mRNA?

The Poly A tail serves to increase the stability of the mRNA molecule. This tail, a sequence of adenine nucleotides added to the 3' end of the mRNA during post-transcriptional modification, plays a critical role in protecting the mRNA from degradation by ribonucleases in the cytoplasm. The longer the Poly A tail, the more stable the mRNA is, which can enhance its lifespan and availability for translation into protein.

This stability is important because it ensures that the mRNA can be efficiently translated into protein over an extended period. If mRNA were to degrade quickly, it would limit protein synthesis, affecting gene expression levels. Additionally, the Poly A tail also aids in the export of mRNA from the nucleus to the cytoplasm, where translation occurs, further highlighting its significance in mRNA metabolism.