Helicase activity for this family has been demonstrated [1] and NTPase activity [2]. This helicase has multiple roles at different stages of viral RNA replication, as dissected by mutational analysis [3].

1: Evolution and taxonomy of positive-strand RNA viruses: implications of comparative analysis of amino acid sequences. Koonin EV, Dolja VV; Crit Rev Biochem Mol Biol 1993;28:375-430. PMID:8269709

2: RNA helicase activity of Semliki Forest virus replicase protein NSP2. Gomez de Cedron M, Ehsani N, Mikkola ML, Garcia JA, Kaariainen L; FEBS Lett 1999;448:19-22. PMID:10217401

3: ATPase and GTPase activities associated with Semliki Forest virus nonstructural protein nsP2. Rikkonen M, Peranen J, Kaariainen L; J Virol 1994;68:5804-5810. PMID:8057461

4: Helicase and capping enzyme active site mutations in brome mosaic virus protein 1a cause defects in template recruitment, negative-strand RNA synthesis, and viral RNA capping. Ahola T, den Boon JA, Ahlquist P; J Virol 2000;74:8803-8811. PMID:10982322