Metallophosphoesterases (MPPEs) are dynamic enzymes that catalyze a variety of cellular reactions and contain a conserved beta-alpha-beta-alpha-beta fold. The MPPE superfamily is divided into two subfamilies: phosphomonoesterases and phosphodiesterases. Each MPPE has a dimetal center located approximately at the C-terminal end of the parallel ∫-strands of the fold. MPPE1 (Metallophosphoesterase 1) is a 396 amino acid multipass membrane enzyme that requires two divalent metals as cofactors. MPPE1 contains a N-terminal signal peptide, a typical metallophosphoesterase domain and a C-terminal transmembrane domain. Expression of MPPE1 seems to be limited to brain. There are five isoforms of MPPE1 that are produced as a result of alternative splicing events.