Transfer of a dense granule protein of Plasmodium falciparum to the membrane of ring stages and isolation of dense granules

Abstract

A 14-kDa protein was localized to the dense granules of Plasmodium falkiparum by immunoelectron microscopy with monoclonal antibody lH1. The protein was present in dense granules in late-stage schizonts and free merozoites. After invasion, the protein was localized exclusively on the membrane of the newly invaded ring. The protein is referred to as RIMA, for ring membrane antigen. The 14-kDa protein was synthesized late in schizogony as determined by immunofluorescence microscopy and immunoblotting. At the

Monitoring Plasmodium falciparum growth and development by UV flow cytometry using an optimized Hoechst‐thiazole orange staining strategy

“…Early trophozoites (late G1 phase) will begin to accumulate RNA as inferred by an increase in TO staining. As parasite DNA replication proceeds (S phase) late trophozoites and schizonts (≥4 nuclei) (40, 49) increasing both DNA and RNA content, should be characterized by both increased HO and TO specific fluorescence. When the parasite reaches its spore‐like, pre‐lytic segmenter stage, DNA synthesis has ceased (G2 phase) and the parasitized erythrocyte has reached maximum levels of HO staining.…”

“…As the parasites begin to replicate their DNA, they are now in a stage known as late trophozoites (lower half of the black oval at 45°). When the erythrocyte contains ≥4 nuclei they are known as schizonts (49) (upper half of the black oval at 45°) and when they reach their maximum DNA levels they enter a G2 phase known as segmenters before erythrocyte lysis. Based upon current understanding of the parasite life cycle it was anticipated that these different stages could be isolated by knowing the level of DNA and RNA expressed by the parasite.…”

etramps, a NewPlasmodium falciparumGene Family Coding for Developmentally Regulated and Highly Charged Membrane Proteins Located at the Parasite–Host Cell Interface

“…In the related apicomplexan Toxoplasma gondii, the rhoptry proteins ROP2, 3, 4, and 7 are inserted into the PVM (Beckers et al, 1994) in a process concomitant with host cell invasion and PVM formation. In P. falciparum, proteins derived from merozoite apical organelles were also found to be associated with the PVM after invasion (Bushell et al, 1988;Sam-Yellowe et al, 1988;Trager et al, 1992) but in contrast to T. gondii, these structures seem to be lost after invasion. We cannot exclude that some ETRAMPs are already inserted into the PVM upon invasion.…”

Protein Trafficking to Apical Organelles of Malaria Parasites – Building an Invasion Machine

“…It has been proposed that this molecule stabilizes spectrin tetramers against dissociation, thus protecting against mechanical and thermal degradations (99,100), and by changing the physical properties of the RBC membrane, perhaps also protects the RBC against multiple infection (101). Another protein known as ring membrane antigen (RIMA) is transported to the plasma membrane of ring‐stage parasites immediately after invasion and appears to play a specific role in the early establishment of the PV (102). Two subtilisin‐like serine proteases, PfSUB1 and PfSUB2, have also been localized in DGs (103,104).…”