“…By convention, the subunits are named using 'RP' for RNAP, 'A', 'B' and 'C' for Pol I, II and III, respectively, and a number (starting from the largest) for the specific subunit; for example, RPA1 is the 1 st (largest) subunit for Pol I. Most yeast Pol II subunits are essential for cell viability, except for the 4 th (RPB4) and 9 th (RPB9) subunits (Archambault & Friesen, 1993;Hull et al, 1995;Sampath & Sadhale, 2005). Within the conserved core, five subunits (1 st , 2 nd , 3 rd , 9 th , 11 th ) are each encoded by a multigene family, having specific paralogs for Pol I, II and III, respectively (Cramer et The compositions of Pol II, IV and V subunits were from previous biochemical studies (Huang et al, 2009;Ream et al, 2009;Law et al, 2011).…”