PI Glycans, GPI anchors, or Glycophospholipid Anchors are protein-lipid anchors present on the cell surface.
GPI anchors are present in many proteins, from enzymes to adhesion molecules, receptors, and antigens and
occur in virtually all mammalian cell types. All GPIs share a core structure of Phosphatidylinositol
glycosidically linked to nonacetylated Glucosamine (GlcN). As Glucosamine usually exists in either
acetylated or sulfated form, the presence of nonacetylated glucosamine is a hallmark of GPI anchors.
The diagram at right depicts the PI Glycan core sugar structure; locations of the linkages of substituents
R1-R8 are noted. The substituents at R1 and R2 are always present, R3 through R8 are only possible substitutions.
click to view substituents in 3D
R1,R2
R3
R4,R7
R5
R6
R8
Site designed and maintained by Aidan Ryan, LECB Structural Glycobiology Section, NCI Frederick, Maryland
