Immuno-EM labeling of KAHRP in knob skeletons. (A). Thick section (average of 50 slices) from a cryotomogram of schizont skeleton labeled with anti-KAHRP antibody 18.2 and 10-nm gold-conjugated secondary antibody. (B) The same field of view shown in (A), with 70 slices of a 3-D model overlaid, describing knob spirals by the first and last turn (green contours), and gold beads as cyan spheres. (C) Sections (30 slices each) through individual knobs in a cryotomogram of schizont skeleton labeled with mAb 18.2 and gold-conjugated secondary antibody, showing spiral structure with radiating pattern and gold labeling on the coat layer. Connected cytoskeleton is also visible. (D) Model showing spirals as first and last turn (green contours) and gold label (cyan spheres) in a cryotomogram of schizont skeleton labeled with anti-KAHRP antibody 18.2. Dashed lines mark the boundaries in x of the volume shown in the side view. (E) Chart showing the average density of gold beads at a given radial distance (in 3-D) from knob spirals in 4 cryotomograms of schizont skeletons labeled with KAHRP antibody 18.2 and 10-nm gold-conjugated secondary antibody.