Schematic illustrations of interactions among minor and major proteins. Interactions are marked here, numbered in Fig. S10, and listed in table S3. (A) Contacts on the inner surface of the capsid. Characters a-f denote the positions of six types of hexon C-extensions. At each vertex, five copies of protein IIIa link five peripentonal hexon trimers and a penton-base pentamer to make a GOS tile (light blue shade). Protein VIII mediates binding among hexons, links GON tiles (gray shade) to GON tiles, and links GON tiles to GOS tiles. (B) Contacts on the outer surface among the four types of hexon trimer (H1, H2, H3, H4) and the four types of protein IX monomer (red, green, yellow, blue) that are inlaid into the canyons at the borders between hexons. Protein IX lashes hexons together to form GON tiles and also links GON tiles.