STRUCTURAL-ANALYSIS OF THE GLYCOSYL-PHOSPHATIDYLINOSITOL MEMBRANE ANCHOR OF THE MEROZOITE SURFACE PROTEIN-1 AND PROTEIN-2 OF PLASMODIUM-FALCIPARUM

Plasmodium falciparum accumulates the two merozoite surface proteins-1 and -2 during schizogony. Both proteins are proposed to be anchored i n membranes by glycosyl-phosphatidylinositol membrane anchors. In this report the identity of these GPI-anchors is confirmed by labelling wi th tritiated precursors and additionally by specific enzymatic and che mical treatments. Detailed structural analysis of the core-glycans sho wed that the GPI-anchors of both proteins possess an extra alpha 1-2 l inked mannose at the conserved trimannosyl-core-glycan. MSP-1 and MSP- 2 labelled with tritiated myristic acid possess primarily radioactive myristic acid at inositol rings in both GPI-anchors. Additionally the hydrophobic fragments released from [H-3]myristic acid labelled GPI-an chors were identified as diacyl-glycerols, carrying preferentially [3H ]palmitic acid in an ester-linkage.