Glycosylphosphatidylinositol (GPI) is a complex glycolipid that anchors many proteins to the cell surface. The biosynthetic pathway of GPI is mediated by sequential addition of sugars and other components to phosphatidylinositol. PIGV
adds the second mannose to the GPI core (Kang et al., 2005).
By database searching for sequences similar to rat Pigv, Kang et al. (2005) identified human PIGV. The deduced 493-amino acid protein has 8 putative transmembrane domains and shares 85% sequence identity with the rat protein. Fractionation of a human lymphoblastoid cell line revealed that PIGV associated with the endoplasmic reticulum (ER). Kang et al. (2005) determined that the N terminus and 2 conserved regions face the ER lumen.