
<ArticleTitle>Effect of mutations in the upstream promoter on the transcription of human <prot>5S rRNA</prot> genes.</ArticleTitle>
<AbstractText>The human <prot>5S rRNA</prot> gene has a 12-mer external promoter, the D box, localized about 30 bp upstream the coding sequence. By site directed mutagenesis 58 different D box promoter mutants were made. While some mutations in the D box allowed full transcription, other mutations decreased the transcriptional activity to 20-50% compared to the bona fide gene, showing the importance of this external promoter in transcription initiation. A number of maxi <prot>5S rRNA</prot> genes were constructed from bona fide genes and D box mutated clones. Transfection of HeLa cells with maxi <prot>5S rRNA</prot> genes showed that the D box is also important for <prot>5S rRNA</prot> gene expression in vivo. Evidence from different eukaryotic cells suggests that expression of <prot>5S rRNA</prot> genes is regulated by external promoters in addition to the internal control region.</AbstractText>
