Figure 1

Organization of the replicase domains in the viral groups studied. The representation is approximately to scale, and incorporates the findings made in this study. See graphical legend (top) for abbreviations. Many members of the alphavirus supergroup encode a polyprotein, which is cleaved into several proteins or expressed as individual proteins, as exemplified by Sindbis virus and brome mosaic virus, respectively. In contrast, the BaMV replicase is not cleaved. For each virus, only proteins or domains containing a MTase-GTase, a protease, an RdRp, or a triphosphatase are shown. Membrane association segments (mb) that are predicted herein, rather than experimentally determined, are indicated by “?”.