Biology of Glycosylphosphatidylinositol (GPI)-anchor Side Chains and Free GPI

Abstract

Glycosylphosphatidylinositol (GPI) is a posttranslational glycolipid modification of proteins that is widely conserved among eukaryotes. There are about 150 types of GPI-anchored proteins (GPI-APs) in mammalian cells. GPI is composed of a common core structure and side chains specific to different organisms. Free GPIs, or protein-unlinked GPIs, are present on some protozoan and mammalian cell surfaces. The biosynthetic pathway of the GPI side chain in mammalian cells has recently been determined and the relationships between free GPIs and some diseases have been identified. Therefore, GPI research is entering a new phase. Here, I introduce recent findings about GPI side chains and free GPIs in mammalian cells.