protein lipidation GPI anchor metabolic process GPI anchor biosynthetic process The chemical reactions and pathways resulting in the formation of a glycosylphosphatidylinositol (GPI) anchor that attaches some membrane proteins to the lipid bilayer of the cell membrane. The phosphatidylinositol group is linked via the C-6 hydroxyl residue of inositol to a carbohydrate chain which is itself linked to the protein via an ethanolamine phosphate group, its amino group forming an amide linkage with the C-terminal carboxyl of the protein. Some GPI anchors have variants on this canonical linkage. GPI/GSI anchor biosynthesis GPI anchor formation GPI anchor synthesis GPI anchor biosynthesis GPI/GSI anchor biosynthetic process GPI anchor anabolism glycosylphosphatidylinositol biosynthesis glycosylphosphatidylinositol biosynthetic process phosphatidylinositol biosynthetic process glycolipid biosynthetic process