<p>These proteins contain one copy of the calcineurin-like phosphoesterase domain (<db_xref db="INTERPRO" dbkey="IPR004843"/>), followed by a carboxyl-terminal extension that is less well conserved. They possess motifs characteristic of a variety of enzymatically active phosphoesterases [<cite idref="PUB00014394"/>], including acid and alkaline phosphatases, phosphoprotein phosphatases, 5'-nucleotidase, bis(5'-nucleosyl)-tetraphosphatase (symmetrical), sphingomyelin phosphodiesterase, 2',3'-cylic-nucleotide 2'-phosphodiesterase, and 3',5'-nucleotide phosphodiesterase CpdA. They appear to be similar to exonuclease SbcD (<db_xref db="INTERPRO" dbkey="IPR004593"/>), but their catalytic activity has not been characterised.</p>