Fig. 3.

Ribbon diagrams of the newly determined protein structures gp7, gp10, gp53, and gp6. Each polypeptide chain is rainbow-colored from blue at the N terminus to red at the C terminus. Protein domains are indicated by roman numerals. Domains II and III of gp10 are shown as cryo-EM density. Helices of gp7 and gp6, involved in the formation of the three-helix coiled-coils located at the interface between wedges, are indicated by red arrows. Also shown diagrammatically is the ring of gp6 dimers that surround the gp27 hub in the dome-shaped baseplate. Each gp6 dimer has a different color. The amino end of each gp6 monomer makes a trimeric coiled-coil with a part of gp7. The wedge boundaries are indicated by a black outline. Each wedge contains one gp6 dimer formed by association of the gp6 C-terminal regions. Contact between the N-terminal regions of gp6 is outlined by a rectangle, whereas the contact between the C-terminal regions of gp6 is outlined by a circle.