exoribonukleaser

Exoribonucleases, often shortened to exoribonucleases or exoribonucleases, are enzymes that degrade RNA molecules from one end. They are a type of ribonuclease, a broader class of enzymes that break down RNA. Unlike endoribonucleases, which cleave RNA internally, exoribonucleases function by progressively removing nucleotides from the 5' or 3' terminus of the RNA strand.

The specific direction of degradation, 5' to 3' or 3' to 5', is determined by the type of exoribonuclease. These enzymes play crucial roles in various cellular processes, including RNA turnover, quality control, and the processing of RNA molecules. For instance, they are involved in the degradation of messenger RNA (mRNA) after translation, ensuring that cellular resources are not wasted on obsolete transcripts. They also participate in the maturation of ribosomal RNA (rRNA) and transfer RNA (tRNA) by trimming excess nucleotides.

In eukaryotes, exoribonucleases are involved in the degradation of non-coding RNAs and the removal of aberrant RNA molecules. Some exoribonucleases are also important for RNA interference (RNAi) pathways, contributing to the silencing of gene expression. Prokaryotes also possess exoribonucleases that are essential for RNA metabolism and defense against foreign nucleic acids. The precise mechanisms and specific substrates of exoribonucleases can vary widely among different organisms and cellular contexts.