Spectrin binding is required for correct knob formation.

(A,B) Sheared membranes prepared from RBCs infected with CS2, K530, K405 and K362 parasite lines at 40 h post-invasion were imaged by SEM and dSTORM (A; anti-KAHRP mAb18.2) or only SEM (B). Images are displayed as 1 x 1 μm zoomed panels. Scale bar: 500 nm. (C) Projections from electron tomograms of negatively-stained preparations of schizont-infected RBCs from the CS2, K530 and K405 lines. The spiral structures were segmented manually, shown as an overlays in the bottom panel. Scale bar: 50 nm. (D) The proportions of knobs containing complete, fragmented or no spiral were recorded (n = 52, 24 and 21 knobs for CS2, K530 and K405 infected RBCs, respectively). Data is presented as a percentage of the total number of recorded knobs.