PfEMP1 surface-exposure and cytoadherence of REX1 transfectants. A. Immunofluorescence microscopy of acetone-fixed RBCs infected with 3D7 and REX1 transfectants. Maurer’s clefts were identified by immunolabeling with anti-SBP1 (green). Anti-PfEMP1 antibodies (red) revealed colocation of the virulence protein with Maurer’s clefts. The nuclei are stained with DAPI (blue). Scale bar = 3 μm. Accumulation of PfEMP1 at the Maurer’s clefts in the 3D7 wildtype parasites, was observed as confirmed by co-labelling with the Maurer’s cleft marker, SBP1. PfEMP1 is also delivered to the Maurer's clefts in the REX11-579, REX1-GFP and REX1Δ371-579-GFP mutant parasite lines. Thus despite the aberrant morphology there is no obvious defect in trafficking of PfEMP1 from the parasite to the stacked Maurer’s clefts.

McHugh E, Batinovic S, Hanssen E, McMillan PJ, Kenny S, Griffin MD, Crawford S, Trenholme KR, Gardiner DL, Dixon MW, Tilley L. A repeat sequence domain of the ring-exported protein-1 of Plasmodium falciparum controls export machinery architecture and virulence protein trafficking. Mol Microbiol. 2015 Aug 24. [Epub ahead of print]