THE EMBRYONIC RNA HELICASE GENE (ERH) - A NEW MEMBER OF THE DEAD BOX FAMILY OF RNA HELICASES

DEAD box proteins share several highly conserved motifs including the characteristic Asp-Glu-Ala-Asp (D-E-A-D in the amino acid single-lette r code) motif and have established or putative ATP-dependent RNA helic ase activity. These proteins are implicated in a range of cellular pro cesses that involve regulation of RNA function, including translation initiation, RNA splicing and ribosome assembly. Here we describe the i solation and characterization of an embryonic RNA helicase gene, ERH, which maps to mouse chromosome 1 and encodes a new member of the DEAD box family of proteins. The predicted ERH protein shows high sequence similarity to the testes-specific mouse PL10 and to the maternally act ing Xenopus An3 helicase proteins. The ERH expression profile is simil ar to that of An3, which localizes to the animal hemisphere of oocytes and is abundantly expressed in the embryo. ERH is expressed in oocyte s and is a ubiquitous mRNA in the 9 days-post-conception embryo, and a t later stages of development shows a more restricted pattern of expre ssion in brain and kidney. The similarities in sequence and in express ion profile suggest that ERH is the murine equivalent of the Xenopus A n3 gene, and we propose that ERH plays a role in translational activat ion of mRNA in the oocyte and early embryo.