Knockout of GEXP07 alters parasite growth and Maurer’s cleft architecture. (A) Infected RBCs were fixed and probed with anti-KAHRP (green) and counter stained with anti-REX1 (red). Nuclei were stained with DAPI (blue). CS2 = parent line. Projections of Z stacks are shown. Scale bar = 5 μm. (B) Quantification of Maurer’s cleft number. The data plotted represent means ± standard errors of the means of results from 3 separate biological experiments. A total of 121 CS2 and 132 GEXP07 cells were quantified (unpaired t test; **** = P < 0.0001). (C) Quantification of the mean fluorescence intensity (MFI) of KAHRP fluorescence (unpaired t test; ****, P < 0.0001). CS2, n = 29 cells. ΔGEXP07, n = 41 cells. Fluorescence values are in arbitrary units (a.u). (D) Parasite growth assay measuring proliferation over 4 asexual cycles. Growth was assessed by staining infected RBCs with SYTO-61 and subsequent flow cytometry analysis. The data have been normalized and are expressed relative to the ΔGEXP07 parasite line (n = 4 experiments performed in triplicate). (E) EqtII-permeabilized wild-type CS2 and GEXP07 knockout transfectants were labeled with antibodies recognizing REX1 followed by immunogold labeling and were prepared for electron microscopy. Images have been cropped around Maurer’s clefts (white arrows). Additional images displaying the Maurer’s cleft morphologies are shown in Fig. S6A. Gold arrows point to gold particles. Scale bar 100 nm. (F) Rendered 3D models of Maurer’s clefts generated from electron tomograms. Red = RBC; magenta stalk = tether; pastel hues = independent clefts. Scale bar = 200 nm. McHugh E, Carmo OMS, Blanch A, Looker O, Liu B, Tiash S, Andrew D, Batinovic S, Low AJY, Cho HJ, McMillan P, Tilley L, Dixon MWA. Role of Plasmodium falciparum Protein GEXP07 in Maurer's Cleft Morphology, Knob Architecture, and P. falciparum EMP1 Trafficking. mBio. 2020 11(2):e03320-19. 