GLYCOSYL-PHOSPHATIDYLINOSITOL MOLECULES OF THE PARASITE AND THE HOST

The glycosyl-phosphatidylinositol (GPI) protein-membrane anchors are u biquitous among the eukaryotes. However, while mammalian cells typical ly express in the order of 100 thousand copies of GPI-anchor per cell, the parasitic protozoa, particularly the kinetoplastids, express up t o 10-20 million copies of GPI-anchor and/or GPI-related glycolipids pe r cell. Thus GPI-family members dominate the cell surface molecular ar chitecture of these organisms. In several cases, GPI-anchored proteins , such as the variant surface glycoprotein (VSG) of the African trypan osomes, or GPI-related glycolipids, such as the lipophosphoglycan (LPG ) of the Leishmania, are known to be essential for parasite survival a nd infectivity. The highly elevated levels and specialised nature of G PI metabolism in the kinetoplastid parasites suggest that the GPI bios ynthetic pathways might be good targets for the development of chemoth erapeutic agents. This article introduces the range of GPI structures found in protozoan parasites, and their mammalian hosts, and discusses some aspects of GPI biosynthesis.