The seven conserved motifs typical of the helicase superfamily II have been identified in the sequences of Escherichia coli protein SecA, an ATPase mediating protein translocation across the inner membrane of the bacterium, and its Bacillus subtilis homolog Div. It is hypothesized that SecA and Div possess an RNA helicase activity and may couple ATP hydrolysis both to membrane translocation of proteins, and to hairpin unwinding in their own mRNAs, leading to the known autogenous regulation of translation.
