RNA processing is an essential process in eukaryotic cells, creating different RNA species from one and the same gene. RNA processing occurs on nearly all kinds of RNAs, including mRNA that codes for proteins, ribosomal RNA, tRNA, snRNAs, and RNA. RNA processing usually occurs co-transcriptionally, and many factors are recruited by the RNA polymerase itself. This stimulates RNA processing by enhancing the correct assembly of factors as the RNA is being produced. Some factors, such as splice factors and cleavage factors for rRNA, are also recruited by the growing RNA-chain. A further link has been established by the transcription rate itself: the low processivity of the RNA.
