TABLE 2.

RNA polymerase subunit orthologs across all four domains of life, with emphasis on the NCLDV^a

^aY, ortholog found in a virus (among the NCLDV, only for vaccinia virus are orthologs named). Pink background, same polypeptide found in all three eukaryotic polymerases. Blue background, dissociable or not associated with the core polymerase. Khaki background, fused subunits. Yellow background, all other subunits. The Iridoviridae are shown by individual genera instead of family because of their divergence at the level of genus. Archaeal nomenclature is from reference 4. TFIIS is shown in gray font for eukaryotic pol I and pol III because it is unclear what role(s) this protein may play for these enzymes (56). All rows of the table are supported by complete proteomes. Table rows are in descending order of number of identified subunits. *, composite pattern over all phycodnaviruses; for individual viruses, see Table 3.