Part 3. Proteomics
3.5. Proteome Diversity
Published Online: 15 OCT 2004
Copyright © 2005 John Wiley & Sons, Ltd
Encyclopedia of Genetics, Genomics, Proteomics and Bioinformatics
How to Cite
Hooper, N. M. 2004. GPI anchors. Encyclopedia of Genetics, Genomics, Proteomics and Bioinformatics. 3:3.5:66.
- Published Online: 15 OCT 2004
Many proteins are attached to the outer surface of the membrane by a glycosyl-phosphatidylinositol (GPI) anchor covalently linked to the C-terminal amino acid. All GPI anchors have the core structure “ethanolamine-PO4-6Manα1-2Manα1-6Manα1-4GlcNH2α1-6myo-inositol-1-PO4-lipid” but vary in the nature of the lipid moiety and in side-chain modifications to the core glycan (see Glycosylphosphatidylinositol anchors- a structural perspective). The GPI anchor is built up by sequential addition of sugars and ethanolamine phosphate to phosphatidylinositol and then transferred by a transamidase enzyme to the protein. Proteins destined to be GPI anchored have an N-terminal signal peptide for translocation into the lumen of the endoplasmic reticulum and a C-terminal signal that directs addition of the GPI anchor. Experimentally, the presence of a GPI anchor can be determined by digestion with bacterial phosphatidylinositol-specific phospholipase C, detection of the cross-reacting determinant, metabolic labeling with components of the anchor, or relative detergent insolubility. In addition to the stable association of a protein with the membrane, GPI anchors convey other properties on proteins including susceptibility to cleavage by phospholipases, association with detergent-insoluble lipid rafts, intracellular targeting, transmembrane signaling, endocytosis via caveolae, and intercellular transfer.
- GPI anchor;
- lipid raft;
- cross-reacting determinant