A Poly A base sequence would be most likely found at the
The addition of a poly A tail to the 3' end is one of the post-transcriptional modifications that occurs in the processing of eukaryotic messenger RNA (mRNA). A cap consisting of a guanosine derivative is attached to the 5' end. Intervening sequences (introns) are removed by splicing. All of these processing events occur in the nucleus of eukaryotes. Prokaryotic mRNA undergoes none of these modifications.
5' end of a prokaryotic messenger RNA (mRNA)
3' end of a prokaryotic mRNA
5' end of a eukaryotic mRNA
3' end of a eukaryotic mRNA