RNA Polymerase I Holoenzyme Assembly of RNA Polymerase I Holoenzyme (human) At the beginning of this reaction, 1 molecule of 'DNA-directed RNA polymerases I, II, and III 17.1 kDa polypeptide ', 1 molecule of 'DNA-directed RNA polymerase I 135 kDa polypeptide ', 1 molecule of 'DNA-directed RNA polymerases I, II, and III 7.0 kDa polypeptide ', 1 molecule of 'DNA-directed RNA polymerase I 16 kDa polypeptide ', 1 molecule of 'DNA-directed RNA polymerase I 40 kDa polypeptide ', and 1 molecule of 'DNA-directed RNA polymerase I largest subunit ' are present. At the end of this reaction, 1 molecule of 'RNA Polymerase I Holoenzyme (Human)' is present.<br><br> This reaction takes place in the 'nucleolus'.<br> Reactome Database ID Release 4373865 Reactome, http://www.reactome.org ReactomeREACT_1773