<p>These conserved bacterial proteins contain one copy of the calcineurin-like phosphoesterase domain (<db_xref db="INTERPRO" dbkey="IPR004843"/>) and possess most of the 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. Although this group appears to be similar to exonuclease SbcD (<db_xref db="INTERPRO" dbkey="IPR004593"/>), their catalytic activity, if any, is speculative.</p>