Table 2. Some RNA helicases studied by single-molecule approaches, in order of appearance in text.

Helicase	Full name (www.uniprot.org)	Subgroup	Biological role	Substrate	Method	Ref.
eIF4A	eukaryotic initiation factor 4A	DEAD-box	translation initiation	dsRNA	AFM, smFRET	80 , 111
Ded1	ATP-dependent RNA helicase DED1	DEAD-box	translation initiation	ssRNA, dsRNA	AFM, smFRET	80 , 140
HCV NS3	Hepatitis C virus non-structural protein NS3	DEAH-box	viral replication	dsRNA/DNA with 3′ ss overhang55,114	Optical tweezers, smFRET*	112 , 115 , 118 , 119
NPH-II	Nucleoside triphosphate phosphohydrolase II	DEAD-box	transcription termination, RNA export146	viral dsRNA	smFRET	121
Mss116	ATP-dependent RNA helicase MSS116, mitochondrial	DEAD-box	splicing	group I and II introns	smFRET	124
RIG-I	retinoic acid inducible gene I	DExD/H-box	RNA interference,176 immune response168	viral dsRNA	PIFE	135
YxiN	ATP-dependent RNA helicase YxiN	DEAD-box	ribosome biogenesis177	23S rRNA178	smFRET	126 - 129

^*Study performed using dsDNA.