Plasmodium falciparum erythrocyte membrane protein 1

Abstract

Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) is a family of proteins present on themembrane surface of red blood cells (RBCs or erythrocytes) that are infected by the malarial parasite Plasmodium falciparum. PfEMP1 is synthesized during the parasite's blood stage (erythrocytic schizogony) inside the RBC, during which the clinical symptoms of falciparum malaria are manifested. Acting as both anantigen and adhesion protein, it is thought to play a key role in the high level of virulence associated with P.falciparum. It was discovered in 1984 when it was reported that infected RBCs had unusually large-sized cellmembrane proteins, and these proteins had antibody-binding (antigenic) properties. An elusive protein, itschemical structure and molecular properties were revealed only after a decade, in 1995. It is now established that there is not one but a large family of PfEMP1 proteins, genetically regulated (encoded) by agroup of about 60 genes called var. Each P. falciparum is able to switch on and off specific var genes to produce a functionally different protein, rendering evasion from the host's immune system. RBCs carryingPfEMP1 on their surface stick to endothelial cells, which facilitates further binding with uninfected RBCs(through the processes of sequestration and rosetting), ultimately helping the parasite to both spread toother RBCs as well as bringing about the fatal symptoms of P. falciparum malaria.