Figure 3.

The Cryo-EM Structures of the BK Virion and VLP

(A) An external view of the virion (left) and VLP (right) shown at contour levels of 0.022 and 0.009, respectively. The electron density maps have been sharpened using a negative B factor correction of (B = −456 and −804 Å²), and the density is colored using a radial scheme shown in Ångströms.

(B) The architecture of a polyomavirus capsid showing how the T = 7d capsid is built from 72 pentamers of VP1, and an identical VP1 polypeptide sequence is found in six distinct quasi-equivalent conformations in the capsid shell (1, red; 2, yellow; 3, green; 4, cyan; 5, blue; and 6, gray).

(C) The cryo-EM structure of the virion (left) and VLP (right) colored according to the scheme in (B), showing the arrangement of different VP1 molecules in three dimensions.