The surface of Leishmania and Trypanosoma is unusual in being coated by a glycocalix that is rich in glycosylated phosphatidylinositol (GPI) glycolipids. In addition to utilizing GPIs as anchors for surface proteins, protozoan parasites of the genus Leishmania and Trypanosoma synthesize two novel classes of GPI: the polydisperse lipophosphoglycan (LPG) and a family of low molecular weight glycoinositolphospholipids (GIPLs). LPG is expressed in high copy number (1-3 X 10 molecules / cell) in the promastigote stage of Leishmania but not in the amastigote stage, which infects mammalian macrophages. LPG has a tetrapartite structure, consisting of a phosphosaccharide core, a variably phosphorylated hexasaccharide glycan core, a lysoalkylphosphatidylinositol anchor and a small oligosaccharide cap.
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