Poly (A) Tail Addition
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Step 1 - Endonuclease cuts the strand
Poly (A) Endonuclease cleaves at the CA downstream of AAUAAA. -The new mRNA strand is now free from RNA Pol II and has an exposed 3' end.
Function of Poly (A) Tail
Protects RNA from degradation, facilitates the release of mRNA into the cytoplasm from the nucleus
Step 2 - Poly (A) Polymerase
Using no template Poly (A) polymerase adds 100-250 Adenosines to the 3' end.
Poly (A) Tail
a sequence of 50-250 adenine nucleotides added onto the 3' end of a pre-mRNA molecule -Begins 20 base pairs downstream of the signal.