THE GLYCOSYLATION OF THE VARIANT SURFACE GLYCOPROTEINS AND PROCYCLIC ACIDIC REPETITIVE PROTEINS OF TRYPANOSOMA-BRUCEI

Trypanosoma brucei, in common with the other African trypanosomes, exh ibits unusual cell-surface molecular architecture, The bloodstream for m of the parasite is coated with a continuous layer of approximately f ive million variant surface glycoprotein (VSG) dimers that provide the parasite with a macromolecular diffusion barrier to guard against lys is by the alternative complement pathway. The procyclic form of the pa rasite has a more diffuse cell-surface coat made up of approximately 2 .5 million copies of procyclic acidic repetitive protein (PARP). Withi n the VSG and PARP coats exist lower-abundance surface glycoproteins s uch as receptors and nutrient transporters. Both the VSG molecules and the PARP molecules are attached to the membrane via glycosylphosphati dylinositol (GPI) membrane anchors and the VSGs and one form of PARP a re N-glycosylated. In this article, the structures of the N-glycans an d the GPI anchors of T. brucei VSGs and PARPs are reviewed and simple models of the surfaces of bloodstream and procyclic trypomastigotes an presented. (C) 1998 Francqui Foundation. Published by Elsevier Scienc e B.V. All rights reserved.