From bacteria to mammals, mutations that generate
premature termination codons have been shown to result
in the reduction in the abundance of the corresponding
mRNA. In mammalian cells, more often than not, the reduction
happens while the RNA is still associated with the nucleus.
Here, it is reported that mutations in the alcohol dehydrogenase
gene (Adh) of Drosophila melanogaster
that generate premature termination codons lead to reduced
levels of cytoplasmic and nuclear mRNA. Unexpectedly, it
has been found that the poly(A) tails of Adh mRNAs
and pre-mRNAs that carry a premature termination codon
are longer than in the wild-type transcript. The more 5′
terminal the mutation is, the longer is the poly(A) tail
of the transcript. These findings suggest that the integrity
of the coding region may be required for accurate mRNA
3′ end processing.