Fig. 3. The triskelion-forming protein IX assembles in a unique way in HAdV-F41.

(A) Surface representation of IX assembly in HAdV-D26 and HAdV-F41 including all ordered protein density. (B) Graphical representation of HAdV-F41 IX-N triskelion assembly. The three IX chain atoms (green, gray, and purple) are shown in stick representation covered by a semitransparent surface. (C) Close-up view of the hydrophobic core at the center of the IX triskelion assembly, formed by residues Phe¹², Phe¹⁷, and Tyr²⁰ of each IX chain. (D) Computational slice through the electron density of HAdV-F41 at pH 7.4, at the position of IX at the local threefold axis. Electron density is white except the proposed density of IX-C, which is highlighted in green. (E) As (D), but at the icosahedral threefold axis. (F) Schematic representation of one possible arrangement of IX-C.