Posttranscriptional Processing of Messenger RNA

Abstract

Posttranscriptional processing is a very important process in eukaryotic mRNA accumulation, although it is often overlooked as a primary means of regulating gene expression [1,30]. Another key point is that in mammalian cells, transcription, processing, and stability are intertwined, and it is often difficult to dissociate an effect on one process from the others. When transcription of bacterial rRNAs and tRNAs is completed, they are immediately ready for use in translation with no additional processing required. Translation of bacterial mRNAs can begin even before transcription is completed owing to the lack of the nuclear-cytoplasmic separation that exists in eukaryotes. An additional feature of bacterial mRNAs is that most are polycistronic, which means that multiple polypeptides can be synthesized from a single primary transcript. This does not occur in eukaryotic mRNAs. In contrast to bacterial transcripts, eukaryotic RNAs (all three classes) undergo significant posttranscriptional processing and are transcribed from genes that contain introns.