
<ArticleTitle>Comparison of the <prot>RNA polymerase III</prot> transcription machinery in Schizosaccharomyces pombe, Saccharomyces cerevisiae and human.</ArticleTitle>
<AbstractText>Multi-subunit transcription factors (TF) direct <prot>RNA polymerase (pol) III</prot> to synthesize a variety of essential small transcripts such as tRNAs, <prot>5S rRNA</prot> and <prot>U6 snRNA</prot>. Use by <prot>pol III</prot> of both TATA-less and TATA-containing promoters, together with progress in the Saccharomyces cerevisiae and human systems towards elucidating the mechanisms of actions of the <prot>pol III</prot> TFs, provides a paradigm for eukaryotic gene transcription. Human and S.cerevisiae <prot>pol III</prot> components reveal good general agreement in the arrangement of orthologous TFs that are distributed along tRNA gene control elements, beginning upstream of the transcription initiation site and extending through the 3' terminator element, although some TF subunits have diverged beyond recognition. For this review we have surveyed the Schizosaccharomyces pombe database and identified 26 subunits of <prot>pol III</prot> and associated TFs that would appear to represent the complete core set of the <prot>pol III</prot> machinery. We also compile data that indicate in vivo expression and/or function of 18 of the fission yeast proteins. A high degree of homology occurs in <prot>pol III</prot>, <prot>TFIIIB</prot>, <prot>TFIIIA</prot> and the three initiation-related subunits of <prot>TFIIIC</prot> that are associated with the proximal promoter element, while markedly less homology is apparent in the downstream <prot>TFIIIC</prot> subunits. The idea that the divergence in downstream <prot>TFIIIC</prot> subunits is associated with differences in <prot>pol III</prot> termination-related mechanisms that have been noted in the yeast and human systems but not reviewed previously is also considered.</AbstractText>
