RNA Polymerase

RNA Polymerases Classification

In eukaryotes, there are four forms of RNA polymerase (I-IV), which are classified on the basis of the type of RNA they produce. RNA polymerase I (Pol I) makes a pre-ribosomal RNA (pre-rRNA 45S), which makes up ~50% of the RNA produced in a cell; RNA polymerase II (Pol II), which makes precursors of mRNAs, most snRNA and microRNAs; RNA polymerase III (Pol III), which makes tRNAs and rRNA 5S, as well as other small RNAs found in the cell. RNA polymerase IV is an ...