Proteins of the Plasmodium falciparum two transmembrane Maurer’s cleft protein family, PfMC-2TM, and the 130 kDa Maurer’s cleft protein define different domains of the infected erythrocyte intramembranous network

Abstract

Plasmodium falciparum Maurer's clefts participate in the transport of macromolecules within the cytoplasm, including the transport of virulence proteins to the erythrocyte membrane surface. We identified a family of genes PfMC-2TM encoding transmembrane proteins located within the intramembranous network of the infected erythrocyte using monoclonal antibody SP1C1. The distribution of the PfMC-2TM protein family within domains of the network was investigated by colocalization and confocal microscopy studies using monoclonal antibody SP1C1 specific for PFMC-2TM and monoclonal antibody SP1A6 specific for the130 kDa Maurer's cleft protein. Peptide-specific antibodies were prepared against six peptides from different domains of PfMC-2TM and used with the Mabs, as well as known antibodies specific to Maurer's clefts proteins (ring-expressed protein and membrane-associated histidine-rich protein 1), the erythrocyte membrane protein 1 (PfEMP-1), and serine-rich antigen in colocalization studies. We show that PfMC-2TM is located in the Maurer's clefts throughout the intracellular blood stage, and immunoelectron microscopy shows domains of PfMC-2TM localized in the parasitophorous vacuole and parasitophorous vacuole membrane. The distribution of the 130 kDa Maurer's cleft protein changes from within the parasite to the clefts during intracellular development as the parasite matures from young trophozoite to segmented schizont.