Figure 1.

The families of the SF1 and SF2. The cladogram was generated from an structure-aided sequence alignment of all SF1 and 2 proteins in yeast and human, described in (3). The alignment can also be found on the RNA helicase primer page of the database. Branch lengths of the cladogram are not to scale. The oval marks uncertainty in the topology. Families containing RNA helicases are marked with a circled R, the other families contain DNA helicases. (T1R, Type 1 restriction enzymes; RHA, RNA helicase A).