Overall view of the circular positive electron densities inside the chloroplast c ring. (A) c14-ring side view. (B) Isometric view of additional electron densities inside the c-ring. (C) A clip of the c-ring slightly above Glu61 residues (colored red). (D) Section clip shows the additional densities inside the c-ring (deep green mesh density map (Fo – Fc) at 3σ). The distance between each of the three circular densities is 5.4 Å, the same as between amino acids Ala 7, Ile 11, Leu 15 and Leu 19. Stroma of the chloroplast is on the top, thylakoid lumen is on the bottom of the picture, c1-subunits are shown as cartoon. The additional densities inside the c-ring are colored as deep green mesh which shows the density map (Fo – Fc) at 3σ.