GLYCOSYLPHOSPHATIDYLINOSITOLS SYNTHESIZED BY ASEXUAL ERYTHROCYTIC STAGES OF THE MALARIAL PARASITE, PLASMODIUM-FALCIPARUM - CANDIDATES FOR PLASMODIAL GLYCOSYLPHOSPHATIDYLINOSITOL MEMBRANE ANCHOR PRECURSORS AND PATHOGENICITY FACTORS

Plasmodium falciparum is the causative agent of malaria tropica in man . Biochemical studies were focused on the asexual, intraerythrocytic s tages of P. falciparum, because of their role in the clinical phase of the disease and the possibility of propagation in a cell culture syst em. In this report, we describe the in-culture labeling of malarial gl ycolipids and the analysis of their hydrophilic moieties. They were id entified as glycosylphosphatidylinositols (GPIs) by: 1) labeling with [H-3]mannose, [H-3]glucosamine, and [H-3]ethanolamine and 2) sensitivi ty toward glycosylphosphatidylinositol-specific phospholipase D, phosp holipase A2, and nitrous acid. Malarial GPIs are shown to be unaffecte d by treatment with phosphatidylinositol-specific phospholipase C, reg ardless of prior treatment with mild base commonly used for inositol d eacylation. Two candidates for putative GPI-anchor precursors to malar ial membrane proteins with the structures nalpha1-2)Manalpha1-2Manalph a1-6Manalpha1-4GlcN-PI (Pf(gl) alpha) and osphate-6Manalpha1-2Manalpha 1-6Manalpha1-4-GlcN-PI (Pf(gl); beta) were identified.