Fig 5.

Rings 1 and 2 of Plasmodium falciparum merozoites contain 34 repeating units. Three subtomogram average (STA) maps of Plasmodium apical rings were generated and shown in A, B, and C. (A) STA map #1 (orange) containing five “bridge” stalks (arrowhead) connecting Ring 1 to Ring 2 was mapped back and aligned into a tomogram at multiple positions to produce the assembled map (grey). (B) STA map #2 (blue) containing three bridge stalks was generated by focus refinement based on the middle bridge stalk and aligned into the assembled map. (C) STA map #3 (yellow) was generated by focus refinement based on Ring 2, showing high densities of Ring 3 surrounding Rings 1 and 2. (D) The assembled map and three STA maps were segmented into repeating units shown in multiple random colors. A single repeating unit from each STA map is presented in two orientations, differing by 180°. Each color represents a repeating unit from each STA map as indicated in the figure. More detailed density features were observed in the STA maps #1 and #2.