Small GTP‐binding proteins in Plasmodium falciparum

Abstract

Summary— During its erythrocytic life cycle Plasmodium falciparum exchanges compounds with host cells through phagocytosis and exocytosis. In eucaryotic cells, small GTP‐binding proteins of the Ras superfamily appear to be involved in different steps of membrane trafficking and in intracellular signals. In this paper, we investigate the Rab4, Rab6 and Ras‐related proteins in P falciparum infected red cells. We report that P falciparum Rab and Ras‐related proteins could be distinguished from their counterparts by iso‐electrofocusing and immunoblotting. The localization of P falciparum Rab 4 and Rab 6 was studied by immunogold electron microscopy on ultrathin frozen sections of infected red blood cells. Rab4 parasite‐relate protein was found associated with the membranes of early endosome‐like structures near the parasite plasma membrane. Rab6‐related protein was associated with the Golgi/trans Golgi network, as already suggested by immunofluorescence microscopy studies and Ras‐related protein was cytoplasmic and plasma membrane‐associated. These results are in accordance with their mammalian counterparts and support the implication of Rab‐related proteins in vesicular trafficking in Plasmodium.