Glycophosphatidylinositol

Glycosylphosphatidylinositol anchor, short GPI anchor, Eng. GPI anchor, are present in all eukaryotic cells. Their main task is to firmly anchor cell-surface glycoproteins on the outside of the plasma membrane. GPI - anchor is attached in the lumen of the endoplasmic reticulum to the terminal carboxyl group of the glycoprotein, wherein the signal sequence coding for the import into the endoplasmic reticulum, is cut off. Because the GPI - anchor interacts with a lipid bilayer of the biomembrane, is prevented from interacting on the other side of the double membrane and contribute to the protein composition the asymmetrical bilayer.

GPI anchor also lead to increased mobility of some proteins on the membrane and promote signal transmission as well as the cellular transport. In addition, they play an important role in the formation of antigens on the plasma membrane and thus lead to the identification of the cell.

The parasite Trypanosoma brucei, because of its variable membrane proteins (variant surface glycoproteins, VSG) are not recognized by the host immune system, which can be made ​​possible by the so-called VSG GPI anchor.

GPI -anchored proteins could be detected by a phospholipase that specifically cleaves phospholipids inositolhaltige.

Furthermore, it was demonstrated that GPI - anchors have a trimannose -glucosamine -inositol - backbone.