<p> This entry represents a small clade of sequences from the metazoa and bacteria. In eukaryotes, this domain exists as an N-terminal fusion to the soluble epoxide hydrolase enzyme and has recently been shown to be an active phosphatase, although the nature of the biological substrate is unclear [<cite idref="PUB00015515"/>]. These appear to be members of the haloacid dehalogenase (HAD) superfamily of aspartate-nucleophile hydrolases by general homology and the conservation of all of the recognised catalytic motifs [<cite idref="PUB00003337"/>] (although the first motif is unusual in the replacement of the more common aspartate with glycine). The variable domain is found in between motifs 1 and 2, indicating membership in subfamily I and phylogeny and prediction of the alpha helical nature of the variable domain indicate membership in subfamily IA.</p>