Glycophosphatidylinositol GPI Anchors

Figure 6 Structure of a GPI anchor. Glycophosphatidylinositol (GPI) anchors are important functional structures on the cell surface. The fatty add phosphatidylinositol is embedded in the exterior leaflet plasma membrane and features a tether consisting of a specific series of monosaccharides and phosphoethanolamine linked to the C-terminus of a protein.

FIG. 2. Common features of glycophosphatidylinositol (GPIs) anchors of glycoproteins. Characteristic sites of chemical and enzymatic reactions of GPIs are shown. EtN, 2-aminoethanol (ethanolamine). 

The discovery that phospholipase C could release alkahne phosphatase from lipid-linked structures on cellular surfaces (39) led to the identification of the glycophosphatidylinositol (GPI) membrane component (40). GPI structures are a synthetic tour de force of nature, combining lipids, carbohydrates, and proteins into a single macromolecule. Certain proteins require GPI anchoring to be functional for example, Ly-6A/E-mediated T-cell activation is critically dependent on its GPI anchor (41), and folate uptake functions efficiently only when its receptors are GPI anchored (42). 

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