(A) (visualized from the outside of the viral particle) The four unique P3 trimers (represented in four different colors) and their arrangement forming the trisymmetron bound by the P30 dimers (in gray). The C-terminal region and the N-terminal region of P3 subunits are colored in red and blue respectively. The highlighted regions show the locking of P30 (in black) by the C-terminal region of the neighboring P3 subunits, leading to the formation of a hinge-like mechanism which is not seen in PRD1. (B) Schematic representation of the P3 trimers and the subunit arrangement to form a hexagonal capsomer (as viewed from outside) and (C), (D), (E,) (F) are aligned to this view. (G) It is the orthogonal view to the schematic (B) and (H), (I), (J), (K) are aligned to this view. Different views of trimer 1 (C,H), trimer 2 (D,I), trimer 3 (E,J) and trimer 4 (F,K) show the variation in the N-terminal (shown as blue cylinders with the arrow heads pointing towards the C-terminal) and C-terminal (shown as red planks with the arrow heads pointing towards the C-terminal) region of P3 subunits. N and C termini are shown as spheres with respective colors. They are colored to match (A). The yellow pentagons are a schematic representation of the penton.