Properties of a mouse ribosomal protein promoter

The three mouse ribosomal protein genes that have been analyzed to date, although evolutionarily unrelated, exhibit some remarkably similar sequence features at their 5' ends, some of which are shared by other genes in the "housekeeping" category. In order to appreciate the significance of these features, we have examined the transient expression of the genes encoding ribosomal proteins L32 and S16, as well as that of a set of 5'-deletion mutants of the L32 gene, in transfected primate cells. Our results reveal two important characteristics of the elements that positively regulate L32 transcription: they do not extend more than 36 nucleotides upstream of the major transcriptional initiation site, and they are insensitive to the presence of cis-linked simian virus 40 enhancer elements. The relevance of these findings to the general design features of housekeeping gene promoters is discussed.