Plasmodium falciparum: asexual erythrocytic stages synthesize two structurally distinct free and protein-bound glycosylphosphatidylinositols in a maturation-dependent manner.

Glycosylphosphatidylinositols represent the predominant class of glycolipids synthesized by the asexual, intraerythrocytic stages of Plasmodium falciparum. These glycolipids have been implicated as malarial toxins involved in parasite-induced release of cytokines, such as tumor necrosis factor-alpha and interleukin-1. Two potential glycosylphosphatidylinositol membrane-anchor precursors with the structures ethanolamine phosphate (mannose-alpha 1,2)mannose-alpha 1,2-mannose-alpha 1,6-mannose-alpha 1,4-glucosamine-inositol(acyl)phosphate diacylglycerol (P.f.alpha) and ethanolamine-phosphate-mannose-alpha 1,2-mannose-alpha 1,6-mannose-alpha 1,4-glucosamine-inositol(acyl)phosphate diacylglycerol (P.f.beta) have been described in P. falciparum. Only one (P.f.alpha) has been demonstrated to serve as an anchor for merozoite surface protein-1 and merozoite surface protein-2. In this report we present data showing that asexual, intraerythrocytic stages of P. falciparum use both glycosylphosphatidylinositols to anchor proteins. The synthesis of the two glycosylphosphatidylinositol membrane anchor precursors and the protein-bound glycosylphosphatidylinositol anchors is tightly regulated and varies throughout the intraerythrocytic development of the asexual stages of P. falciparum. The glycosylphosphatidylinositol membrane-anchor precursor P.f.beta is synthesized and transferred to protein predominantly in trophozoite stages (about 30 h).