Nonsense mutations in the alcohol dehydrogenase gene of Drosophila melanogaster correlate with an abnormal 3 ' end processing of the corresponding pre-mRNA

From bacteria to mammals, mutations that generate premature termination cod ons have been shown to result in the reduction in the abundance of the corr esponding mRNA. In mammalian cells, more often than not, the reduction happ ens while the RNA is still associated with the nucleus. Here, it is reporte d that mutations in the alcohol dehydrogenase gene (Adh) of Drosophila mela nogaster that generate premature termination codons lead to reduced levels of cytoplasmic and nuclear mRNA. Unexpectedly, it has been found that the p oly(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 findi ngs suggest that the integrity of the coding region may be required for acc urate mRNA 3' end processing.