Post GPI Attachment To Proteins 1 (PGAP1)

PGAP1 catalyzes the inositol deacylation of glycosylphosphatidylinositol (GPI) at an early step in GPI biosynthesis. Inositol deacylation is essential for the generation of mature GPI capable of attachment to proteins.The human and rat proteins share 90% sequence identity and have an identical lipase consensus motif with a putative catalytic serine. Both proteins share similarity with the yeast ortholog, Bst1p. Sucrose-density centrifugation followed by Western blot analysis of fractions localized Pgap1 to the endoplasmic reticulum (ER). Pgap1 has a membrane orientation with the N terminus on the cytoplasmic side and the lipase motif oriented to the luminal side of the ER, consistent with what would be predicted for inositol deacylase.