FIG. 52.

The positions of the proteins of adenovirus are shown by difference imaging with an atomic model based on the high-resolution structure of the adenovirus hexon protein (blue in panels A and B). An external view of the virion along the twofold axis (A) shows the position of the trimers of polypeptide IX which link the group of nine hexons in a single facet and polypeptide IIIa which links adjacent facets. The penton base I is represented in yellow with the fiber being shown in green. The view from the interior of the virion shows polypeptide IIIa, which passes through the layer of hexons, and of polypeptide VI hexamers near the penton base. These positions are shown schematically in panel C, where the triangular top and hexagonal base of hexon and the pentagonal penton base are shown in white. The polypeptide IX trimers are shown as black triangles. The polypeptide VI hexamers are shown as black circles, and the hexon layer spanning polypeptide IIIa is shown as filled black bars. The fit between the hexon density seen in the high-resolution structure and that in the reconstruction is shown for the region surrounding the penton base in panel D. Adapted from reference 298 with the permission of the publisher.