Phosphatidylinositol-glycans (PIGs) are multi-pass transmembrane proteins that localize to the endoplasmic reticulum. PIGs exhibit various functions, but all are crucial for the biosynthesis of the glycosylphosphatidylinositol (GPI)-anchor. Some PIG proteins are components of the GPI transamidase complex and play a role in the recognition of either the GPI attachment signal or the lipid portion of GPI. Other PIGs belong to the glycosyltransferase complex and function in the transfer of N-acetylglucosamine (GlcNAc) to phosphatidylinositol (PI). A variety of other PIGs play distinct roles in GPI synthesis including mannosylation of the GPI-anchor. PIG-W (Phosphatidylinositol-glycan biosynthesis class W protein) is a 504 amino acid multi-pass membrane protein that functions in the third step of GPI biosynthesis and acylates the inositol ring of phosphatidylinositol.
phosphatidylinositol glycan anchor biosynthesis, class W; phosphatidylinositol glycan, class W; Phosphatidylinositol-glycan biosynthesis class W protein; PIG-W