RNA polymerase III
= RNA polymerase III
{c}
<RNA polymerase III> is a eukaryotic <RNA polymerase> that transcribes several small functional <RNAs>, including <transfer RNA> and 5S <ribosomal RNA>. It is distinct from <RNA polymerase I>, which makes the large precursor of most other <ribosomal RNAs>, and from <RNA polymerase II>, which transcribes protein-coding <genes> and many noncoding <RNAs>.
In 1974, <Roberto Weinmann> and <Robert G. Roeder> compared inhibition of RNA synthesis in isolated nuclei with the characteristic inhibitor sensitivity of separated <RNA polymerases>. The behaviour of <transfer RNA> and 5S <ribosomal RNA> synthesis matched <RNA polymerase III>, assigning particular RNA products to an enzymatic activity rather than grouping all nuclear <transcription> together.<Role of DNA-Dependent RNA Polymerase III in the Transcription of the tRNA and 5S RNA Genes by Roberto Weinmann and Robert G. Roeder>[Abstract, alpha-amanitin sensitivity and isolated-nucleus transcription]{ref} This division of labour explains how production of translation machinery can be regulated separately from production of <messenger RNA>.