<p>This entry represents type 2 phosphatidic acid phosphatase (PAP2; <db_xref db="EC" dbkey="3.1.3.4"/>) enzymes, such as phosphatidylglycerophosphatase B <db_xref db="EC" dbkey="3.1.3.27"/> from <taxon tax_id="562">Escherichia coli</taxon>. PAP2 enzymes have a core structure consisting of a 5-helical bundle, where the beginning of the third helix binds the cofactor [<cite idref="PUB00024099"/>]. PAP2 enzymes catalyse the dephosphorylation of phosphatidate, yielding diacylglycerol and inorganic phosphate [<cite idref="PUB00036051"/>]. In eukaryotic cells, PAP activity has a central role in the synthesis of phospholipids and triacylglycerol through its product diacylglycerol, and it also generates and/or degrades lipid-signalling molecules that are related to phosphatidate.</p><p>Other related enzymes have a similar core structure, including haloperoxidases such as bromoperoxidase (contains one core bundle, but forms a dimer), chloroperoxidases (contains two core bundles arranged as in other family dimers), bacitracin transport permease from <taxon tax_id="1402">Bacillus licheniformis</taxon>, glucose-6-phosphatase from rat. The vanadium-dependent haloperoxidases exclusively catalyse the oxidation of halides, and act as histidine phosphatases, using histidine for the nucleophilic attack in the first step of the reaction [<cite idref="PUB00010620"/>]. Amino acid residues involved in binding phosphate/vanadate are conserved between the two families, supporting a proposal that vanadium passes through a tetrahedral intermediate during the reaction mechanism.</p>