Glycosylphosphatidylinositols Synthesized by Asexual Erythrocytic Stages of the Malarial Parasite, Plasmodium falciparum

Plasmodium falciparum is the causative agent of malaria tropica in man. Biochemical studies were focused on the asexual, intraerythrocytic stages of E? falciparum, because of their role in the clinical phase of the disease and the possibility of propagation in a cell culture system. In this report, we describe the in-culture labeling of malarial glycolipids and the analysis of their hydrophilic moieties. They were identified as glycosylphosphatidylinositols (GPIs) by: l) labeling with [SH]mannose, [SH]glucosamine, and [SHlethanolamine and 2) sensitivity toward glycosylphosphatidylinositolspecific phospholipase D, phospholipase A2, and nitrous acid. Malarial GPIs are shown to be unaffected by treatment with phosphatidylinositol-specific phospholipase C, regardless of prior treatment with mild base commonly used for inositol deacylation. Two candidates for putative GPI-anchor precursors to malarial membrane proteins with the structures ethanolamine-phosphate6(Manal-2)Manal-2Manal-6Mana14GlcN-P1 (Pfgl a) and ethanolamine-phosphate-6Manal-2Manal-6Manal-4-GlcN-PI (Pfgl /3) were identified.