Fig. 4.

CR9501 and motavizumab Fabs cannot simultaneously bind to closed, trimeric F. a Monomeric prefusion F-CR9501 structure is shown in ribbons with the F₁ subunit colored blue and the F₂ subunit colored green. The CR9501 heavy and light chains are shown as dark pink and light pink ribbons, respectively. Motavizumab Fab is modeled onto the prefusion F monomer using the previously solved structure (PDB ID:3IXT) and is shown in ribbons with the heavy and light chains colored orange and tan, respectively. b The two additional protomers of the prefusion F trimer were generated using the C3 symmetry observed in previous crystal structures and are shown as molecular surfaces. c A 90° rotation about the horizontal axis of the complex shown in (b), viewed looking toward the viral membrane. d A second asymmetric unit from the crystal structure, composed of one prefusion F protomer and one CR9501 Fab, and one modeled motavizumab Fab were aligned with a neighboring protomer of the biological trimer and are shown as transparent molecular surfaces. An interprotomeric clash is observed between CR9501 and motavizumab in the context of the prefusion F trimer