| Primary Identifier | IPR014014 | Type | Domain |
| Short Name | RNA_helicase_DEAD_Q_motif |
| description | RNA helicases from the DEAD-box family are found in almost all organisms andhave important roles in RNA metabolism such as splicing, RNA transport,ribosome biogenesis, translation and RNA decay. They are enzymes that unwinddouble-stranded RNA molecules in an energy dependent fashion through thehydrolysis of NTP. DEAD-box RNA helicases belong to superfamily 2 (SF2) ofhelicases. As other SF1 and SF2 members they contain seven conserved motifswhich are characteristic of these two superfamilies [].DEAD-box is named after the amino acids of motif II or Walker B (Mg2+-bindingaspartic acid). Besides these seven motifs, DEAD-box RNA helicases contain aconserved cluster of nine amino-acids (the Q motif) with an invariantglutamine located N-terminally of motif I. An additional highly conserved butisolated aromatic residue is also found upstream of these nine residues [].The Q motif is characteristic of and unique to DEAD box family of helicases.It is supposed to control ATP binding and hydrolysis, and therefore itrepresents a potential mechanism for regulating helicase activity.Several structural analyses of DEAD-box RNA helicases have been reported [, ]. The Q motif is located in close proximity to motif I. Theconserved glutamine and aromatic residues interact with the ADP molecule.Some proteins known to contain a Q motif:Eukaryotic initiation factor 4A (eIF4A). An ATP-dependent RNA helicasewhich is a subunit of the eIF4F complex involved in cap recognition andrequired for mRNA binding to ribosome.Various eukaryotic helicases involved in ribosome biogenesis (DBP3, DRS1,SPB4, MAK5, DBP6, DBP7, DBP9, DBP10).Eukaryotic DEAD-box proteins involved in pre-mRNA splicing (Prp5p, Prp28pand Sub2p).DEAD-box proteins required for mitochondrial genome expression (MSS116 andMRH4).Fungi ATP-dependent RNA helicase DHH1. It is required for decapping andturnover of mRNA.Fungi ATP-dependent RNA helicase DBP5. It is involved in nucleo-cytoplasmictransport of poly(A) RNA.Bacterial ATP-dependent RNA helicase rhlB. It is involved in the RNAdegradosome, a multi-enzyme complex important in RNA processing andmessenger RNA degradation.Bacterial cold-shock DEAD box protein A.This entry represents a region stretching from the conserved aromatic residue to one amino acid after the glutamine of the Q motif. |
