What is Polyadenylation?
Polyadenylation is a crucial post-transcriptional modification in eukaryotic cells where a sequence of adenine nucleotides (the poly(A) tail) is added to the 3' end of messenger RNA.
1. Initial Transcription
5' ...AAUAAA... 3'
The process begins with recognition of the polyadenylation signal sequence (AAUAAA) near the 3' end of the pre-mRNA.
2. Cleavage
5' ...AAUAAAâ–¼... 3'
The pre-mRNA is cleaved at a specific site, typically 10-30 nucleotides downstream from the signal sequence.
3. Tail Addition
5' ...AAUAAAAAAAAAAAAAAAAAAAAAAAAAA 3'
Poly(A) polymerase adds approximately 200-250 adenine nucleotides to form the poly(A) tail.
Why is it Important?
- Protects mRNA from degradation
- Assists in export from nucleus to cytoplasm
- Aids in translation initiation
- Influences mRNA stability and protein production
Learn More About RNA Processing