Cleavage and polyadenylation of a eukaryotic pre-messenger RNA requires recognition of a specific upstream sequence element by cleavage specificity factors. The consensus sequence serving this signal is:
- A TATAAT located about 25 bp upstream of the transcription start site
- B AAUAAA located 10 to 30 nucleotides upstream of the cleavage site ✓
- C GGGCGG located in the promoter proximal region
- D UAAUGA located within the terminal exon coding sequence
Correct answer: B. AAUAAA located 10 to 30 nucleotides upstream of the cleavage site
Explanation
The highly conserved hexamer AAUAAA, produced from the AATAAA coding strand sequence roughly 10 to 30 nucleotides upstream of the polyadenylation site, is bound by cleavage and polyadenylation specificity factor (CPSF), which recruits the cleavage complex and poly(A) polymerase. The TATAAT box is the prokaryotic -10 promoter element and GGGCGG is the GC box binding Sp1 in promoters; both act in initiation, not transcript end formation.
Reference: Lewin's Genes, 12th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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