Polyadeniláció

Polyadeniláció is a crucial post-transcriptional modification in eukaryotic gene expression. It involves the addition of a string of adenine nucleotides, known as a poly(A) tail, to the 3' end of messenger RNA (mRNA) precursors. This process is catalyzed by an enzyme called poly(A) polymerase.

The poly(A) tail plays a significant role in the maturation and function of mRNA. It protects the mRNA from degradation by cellular nucleases, thereby increasing its stability and lifespan in the cytoplasm. Furthermore, the poly(A) tail is essential for the efficient export of mRNA from the nucleus to the cytoplasm, where protein synthesis occurs. It also plays a role in the initiation of translation by interacting with proteins that bind to the 5' cap of the mRNA.

The length of the poly(A) tail can vary and is dynamically regulated. Shorter tails are generally associated with less stable mRNA, while longer tails can indicate more stable transcripts. This regulation allows cells to fine-tune gene expression levels by controlling the abundance of specific mRNAs.

While predominantly found in eukaryotes, polyadeniláció is not a universal feature of all RNA molecules. It is primarily associated with mRNAs, but also occurs in some non-coding RNAs. The process is highly conserved across eukaryotic species, highlighting its fundamental importance in cellular biology.