FIG. 4.

The RGD-binding integrin domains form the ring of density over the penton base in the HAdV12/αvβ5 structure. (A) The two RGD-binding integrin domains, αv chain β-propeller (blue) and β chain I domain (red), together with the RGD residues (green) from the αvβ3/RGD crystal structure (PDB-ID 1L5G), are shown modeled over the HAdV2 penton base crystal structure (PDB-ID 1X9T). One monomer of penton base is shown in gold, the rest in gray, and the fiber peptides are depicted as wide black ribbons. The missing residues in the penton base RGD loop are represented by dashed lines. (B) The penton base is shown with four docked copies of the two-domain integrin unit. (C) The penton base is shown with simulated density (light blue) generated from the integrin models in panel B with fivefold averaging and filtered to 27-Å resolution.