DEDDy 3'-5' exonuclease domain of Drosophila Egalitarian (Egl) and similar proteins
The Egalitarian (Egl) protein subfamily is composed of Drosophila Egl and similar proteins. Egl is a component of an mRNA-binding complex which is required for oocyte specification. Egl contains a DEDDy-type DnaQ-like 3'-5' exonuclease domain possessing three conserved sequence motifs termed ExoI, ExoII and ExoIII, with a specific YX(3)D pattern at ExoIII. The motifs are clustered around the active site and contain four conserved acidic residues that serve as ligands for the two metal ions required for catalysis. The conservation of this subfamily throughout eukaryotes suggests that its members may be part of ancient RNA processing complexes that are likely to participate in the regulated processing of specific mRNAs. Some members of this subfamily do not have a completely conserved YX(3)D pattern at the ExoIII motif.