Evolutionary conservation of largest RNA polymerase subunits. Sequences from the largest subunits of the indicated RNA polymerases were aligned with the CLUSTAL W (v. 1.6) program (Thompson et al. 1994) with the default parameter settings. The percentages of amino acids identical between the human RNA polymerase III sequence and the various largest subunits are indicated on the right. P1, P2, and P3 refer to RNA polymerases I, II, and III, respectively. The references for the sequences are as follows: E. coli (Ec) β′ (Ovchinnikov et al. 1982); H. halobium (Hh) A and C polypeptides (Leffers et al. 1989); T. brucei (Tb) P2 (Smith et al. 1989a); S. cerevisiae (Sc) P2 (Allison et al. 1985); C. elegans (Ce) P2 (Bird and Riddle 1989); D. melanogaster (Dm) P2 (Jokerst et al. 1989); M. musculus (Mm) P2 (Ahearn et al. 1987); human (Hs) P2 (Wintzerith et al. 1992); Tb P3 (Smith et al. 1989a); Sc P3 (Allison et al. 1985); Tb P1 (Smith et al. 1989a); Sc P1 (Memet et al. 1988).
