Polyadenylic acid addition sites in the adenovirus type 2 major late transcription unit.

The cytoplasmic mRNAs which are transcribed from the major late adenovirus promoter can be arranged into five 3'-coterminal families, L1 to L5. We have defined the polyadenylation sites of the mRNAs that belong to the five families at the nucleotide level. From the results, the following conclusions can be made. (i) The hexanucleotide sequence AAUAAA is present at the 3' end of all late adenovirus type 2 mRNAs and precedes the site of polyadenylation by 12 to 30 nucleotides. (ii) Between one and three A residues are present in the genomic sequence at the polyadenylation site. (iii) A sequence with the composition (T)n (A)p (T)q (n, p, q greater than or equal to 1) is found 4 to 24 nucleotides beyond all the adenovirus-specific polyadenylation sites except the 3'-coterminal family L4. This sequence is also found beyond many cellular polyadenylation sites. (iv) The L1 and L2 polyadenylation sites are very similar in structure. The other polyadenylation sites show no apparent sequence relationship, except for the hexanucleotide sequence.