Knob membranes have a distinct distribution of membrane proteins. Cryoscanning EM images of freeze-fractured schizont coated with 4 nm chromium, showing erythrocyte membrane proteins. The knobs are clearly recognizable as indentations (A) or protrusions (B). Membrane proteins are visible as small lighter-shaded bumps forming various patterns on the surface. (A) E-face (inside of the outer membrane leaflet). (B) P-face (outside of inner membrane leaflet). Knobs are indicated by white arrowheads. (C) Schematic of the knob structure, showing the spiral with coat layer underlying the erythrocyte membrane, and erythrocyte spectrin connecting to the outside of the coat layer. Membrane proteins are present at the knob apex and in the surrounding erythrocyte membrane, but are otherwise sparse in the knobs.