Mature messenger RNA
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Mature messenger RNA, often abbreviated as mature mRNA is a eukaryotic RNA transcript that has been spliced and processed and is ready for translation in the course of protein synthesis. Unlike the eukaryotic RNA immediately after transcription known as precursor messenger RNA, mature mRNA consists exclusively of exons and has all introns removed.
Mature mRNA is also called "mature transcript", "mature RNA" or "mRNA".
The production of a mature mRNA molecule occurs in 3 steps:
- During capping, a 7-methylguanosine residue is attached to the 5'-terminal end of the primary transcripts. This is otherwise known as the GTP or 5' cap, and is used for the stability and attachment point for ribosomes.
- In polyadenylation, a poly-adenosine tail of about 200 adenylate residues is added by a nuclear polymerase post-transcriptionally. This is known as a Poly-A tail and is used for stability and guidance, so that the mRNA can exit the nucleus and find the ribosome.
- RNA splicing removes the non-coding RNA introns leaving behind the exons, which are then spliced and joined together to form the final mRNA.