The knob protein KAHRP assembles into a ring-shaped structure that underpins virulence complex assembly
Fig 5
PfEMP1 associates with knobs laterally.
(A) Sheared membranes prepared from RBCs infected with PfEMP1A-GFP transfectants at 20 h post-invasion. Samples were imaged by SEM and dSTORM (anti-GFP). STORM-SEM shows fluorescent foci at knobs (blue arrows), adjacent to knobs (yellow arrows) or independent from knobs (white arrows). Scale bar: 500 nm. (B) Total number of PfEMP1A-GFP foci on sheared membranes at 20, 24 and 30 h post-invasion. (C) Knob counts from sheared membranes viewed by SEM. (D) Quantitation of the number of fluorescent anti-GFP foci and SEM knobs per μm2 from RBC membranes infected with A4 PfEMP1A-GFP parasites at 20, 24 and 30 h post-invasion (n = 11, 12 and 10 membranes, respectively). Data plotted as fluorescent foci at a knob (<50 nm, blue), adjacent to a knob (50–100 nm, yellow) or independent from knobs (>100 nm, white). See S10B Fig for explanatory diagram.