English: Branch 3 of the RNA virus RNA-dependent RNA polymerases (RdRps): alphavirus superfamily and radiation of related tombusviruses, nodaviruses, and unclassified viruses and flavivirus supergroup. (A) Phylogenetic tree of the virus RdRps showing ICTV-accepted virus taxa and other major groups of viruses. Approximate numbers of distinct virus RdRps present in each branch are shown in parentheses. Symbols to the right of the parentheses summarize the presumed virus host spectrum of a lineage. Green dots represent well-supported (≥0.7) branches, whereas yellow dots correspond to weakly supported branches. Inv., viruses of invertebrates (many found in holobionts, making host assignment uncertain); myco., mycoviruses; uncl., unclassified. (B) Genome maps of a representative set of branch 3 viruses (drawn to scale) showing color-coded major conserved domains. Where a conserved domain comprises only a part of the larger protein, the rest of this protein is shown in light gray. The locations of such domains are approximated (indicated by fuzzy boundaries). C, nucleocapsid protein; CapE, capping enzyme; CP-Spro, capsid protein-serine protease; E, envelope protein; fCP, divergent copies of the capsid protein forming filamentous virions; Hsp70h, Hsp70 homolog; MP, movement protein; NS, nonstructural protein; nsP2 to nsP3, nonstructural proteins; Ppro, papain-like protease; prM, precursor of membrane protein; rCP, capsid protein forming rod-shaped virions; RiS, RNA interference suppressor; S1H, superfamily 1 helicase; S2H, superfamily 2 helicase; SJR2, single jelly-roll capsid proteins of type 2; Spro, serine protease; vOTU, virus OTU-like protease; NS, nonstructural protein. Distinct hues of same color (e.g., green for MPs) are used to indicate the cases when proteins that share analogous function are not homologous.