GPI-anchored proteins and glycoconjugates segregate into lipid rafts in Kinetoplastida.

Abstract

The plasma membranes of the divergent eukaryotic parasites, Leishmania and Trypanosoma, are highly specialised, with a thick coat of glycoconjugates and glycoproteins playing a central role in virulence. Unusually, the majority of these surface macro-molecules are attached to the plasma membrane via a glycosylphosphatidylinositol (GPI) anchor. In mammalian cells and yeast, many GPI-anchored molecules associate with sphingolipid and cholesterol-rich detergent-resistant membranes, known as lipid rafts. Here we show that GPI-anchored parasite macro-molecules (but not the dual acylated Leishmania surface protein (hydrophilic acylated surface protein) or a subset of the GPI-anchored glycoinositol phospholipid glycolipids) are enriched in a sphingolipid/sterol-rich fraction resistant to cold detergent extraction. This observation is consistent with the presence of functional lipid rafts in these ancient, highly polarised organisms.