Metallophosphoesterase 1 (MPPE1), also known as PGAP5, acts as a phosphodiesterase removing an ethanolamine phosphate (EtN-P) from mannose 2 of the glycosylphosphatidylinositol (GPI) anchor, thus permitting efficient endoplasmic reticulum (ER) to Golgi transport of GPI proteins[]. Before GPI-anchored proteins exist the ER, two remodeling reaction, inositol deacylation by PGAP1 and removal of the second EtNP by PGAP5, occur in mammalian cells. The MPPE1 gene has been identified as a candidate susceptibility gene for Bipolar disorder [].MPPE1 belongs to the metallophosphatase (MPP) superfamily. MPPs are functionally diverse, but all share a conserved domain consisting of a double β-sheet sandwich with a di-metal active site made up of residues located at the C-terminal side of the sheets. This domain is thought to allow for productive metal coordination.
