<p>This group of conserved proteins from bacteria and archaea contain one copy of the calcineurin-likephosphoesterase domain. Many members possess motifs characteristic of avariety of enzymatically active phosphoesterases [<cite idref="PUB00014394"/>], including acid and alkalinephosphatases, phosphoprotein phosphatases, 5'-nucleotidase, bis(5'-nucleosyl)-tetraphosphatase (symmetrical),sphingomyelin phosphodiesterase, 2',3'-cylic-nucleotide 2'-phosphodiesterase, and the 3',5'-nucleotidephosphodiesterase CpdA. In others, the calcineurin-like phosphoesterase domain is poorly conserved and residuesthought to be essential are not preserved.</p>