A single U leads to G transversion in the 3' consensus sequence AAUAAA of the 
adenovirus early region 1A gene was constructed and the effect of this mutation 
on processing of the 3' end of the nuclear early region 1A RNAs was analysed. 
The results demonstrate that the intact AAUAAA is not required for RNA 
polyadenylation but is required for the cleavage step preceding polyadenylation 
to occur efficiently.