polüadenüleerimist

Polüadenüleerimist is a biological process that occurs in eukaryotic cells. It involves the addition of a tail of adenosine nucleotides, known as a poly-A tail, to the 3' end of messenger RNA (mRNA) molecules. This process is a crucial step in post-transcriptional gene regulation.

The poly-A tail is not encoded in the DNA template but is added by an enzyme called poly-A polymerase after transcription is complete. The addition of the poly-A tail plays a significant role in mRNA stability and longevity. It protects the mRNA from degradation by cellular nucleases, thus increasing its lifespan and allowing for more protein synthesis.

Furthermore, the poly-A tail is involved in the export of mRNA from the nucleus to the cytoplasm, where protein synthesis takes place. It also plays a role in the initiation of translation, the process by which ribosomes read the mRNA sequence to build proteins. The length of the poly-A tail can vary, and changes in its length can affect the efficiency of translation and the overall gene expression.

While a canonical poly-A tail is typically between 100-250 nucleotides long, its exact length can be regulated by various cellular signals. This regulation allows cells to fine-tune gene expression in response to developmental cues or environmental changes. The polyadenylation process is thus a fundamental mechanism for controlling the flow of genetic information from DNA to protein.