The C-terminal extension of CrhR-like helicases contains a unique, highly conserved sequence motif. (a) Alignment of the C-terminal extensions of selected CrhR-like DEAD-box proteins generated by muscle. The final conserved motif in the DEAD-box helicase core, motif VI, HRIGRXXR, is indicated with a grey background. The unique conserved sequence motif characteristic of CrhR-like helicases is indicated in bold, with amino acids coloured based on their chemical properties. (b) Sequence logo of the conserved CrhR-specific sequence motif, with the size of the amino acid indicating its conservation. The sequence logo was generated from an alignment of all 185 CrhR-like DEAD-box RNA helicase sequences using WebLogo 3 [47].