Exoribonukleasen

Exoribonucleases, often abbreviated as exoribonucleases or simply exo-RNases, are a class of enzymes that catalyze the breakdown of RNA molecules by progressively cleaving nucleotides from one end of the RNA strand. This process is known as exohydrolysis. Unlike endoribonucleases, which cleave RNA internally, exoribonucleases act at the termini. There are two main types based on their directionality: 5' to 3' exoribonucleases, which degrade RNA starting from the 5' end, and 3' to 5' exoribonucleases, which degrade RNA from the 3' end. Many exoribonucleases are involved in essential cellular processes. For instance, they play a crucial role in RNA turnover and degradation, ensuring that cellular RNA levels are regulated. This degradation is important for removing damaged or no longer needed RNA molecules. They also participate in RNA processing, where specific regions of RNA molecules are trimmed or removed. In eukaryotes, exoribonucleases are involved in the maturation of various RNA species, including ribosomal RNA (rRNA) and transfer RNA (tRNA). Furthermore, exoribonucleases are critical components of RNA surveillance pathways, which identify and eliminate aberrant or non-functional RNA molecules. Dysregulation of exoribonuclease activity can have significant consequences, contributing to various diseases, including certain cancers and developmental disorders.