FIG. 5.
Closure of the penton channel in the virion. (a) Sectional view of the B-capsid penton. In the middle of the channel, densities from the VP5 subunits (arrows) protrude inward, resulting in a constriction. (b) Sectional view of the virion capsid penton. The arrow indicates the closure in the axial channel at the region that is constricted in the B-capsid channel. Also indicated are the densities attributed to tegument (T) and viral DNA.