Glycosylphosphatidylinositol (GPI) anchors are commonly found in all eukaryotic cells. However, compared to mammalian cells, protozoan parasites express about one hundred times more GPI glycolipids per cell. GPIs are commonly employed by the parasites to anchor surface antigens on the extracellular membrane, although not protein-linked or free GPIs can also be found. Parasitic GPIs are believed to regulate the immune response of the host by protozoa. However, a detailed structure function relationship of GPIs has not been established due to the difficulties in obtaining sufficient quantities of homogeneous material. This review summarizes the structures of characterized parasitic GPIs and their roles in triggering host immune responses. We focus on the recent progress in the chemical synthesis of GPI anchors and application of synthetic materials for development of vaccines and glycan arrays.
Post-translational modification of proteins with glycosylphosphatidylinositol (GPI) is mediated by a mechanism that is conserved in all eukaryotes. GPI-anchored proteins are characterized by their association with specialized membrane domains called “lipid rafts,” and the GPI-anchors are thought to regulate their intracellular trafficking pathways. These characteristics are regulated by the structural properties of GPI-anchors, remodeling enzymes and recognition molecules. The biogenesis of GPI-anchored proteins occurs in the ER, following which they are transported to the plasma membrane via the Golgi apparatus. During transport, the structures of the GPI-anchors are remodeled. In this minireview, the structural remodeling of mammalian GPI-anchors and regulation of the transport and localization of GPI-anchored proteins are described.
Molecular design, chemical synthesis, and biological evaluation of several organic small molecules, which can target-selectively photodegrade oligosaccharides by irradiation with a specific wavelength of light under mild conditions without any additives, are introduced. These novel class of photochemical agents promise bright prospects for finding not only molecular-targeted bioprobes for understanding of the structure-activity relationships of oligosaccharides but also novel therapeutic drugs targeting biologically active oligosaccharides.