Knob skeletons make multiple connections to the erythrocyte cytoskeleton. (A) Schizont skeleton with knob skeletons in vitreous ice; average of 50 slices from an NAD-filtered cryotomogram. (B) Uninfected erythrocyte skeleton; average of 30 slices. (C) Enlarged view of the boxed region in (A), average of 30 slices, showing 4 knob skeletons and surrounding cytoskeleton. (D) The same region shown in (B), with superimposed model of knobs and associated material in 3-D. Spiral strands are partially traced as green tubes and the coating layer of the knob skeletons is outlined by magenta contours. Points of connection with the surrounding cytoskeletal material (dark blue tubes) are marked by yellow spheres. (E) Orthogonal views of a model of a typical knob skeleton (top right in C-D). In the side view (top), the estimated location of the cell membrane before detergent extraction, based on Figure 4, is marked by a dashed line. The outer surface of the coat layer has been rendered as a mesh (magenta).