Figure 3. Structure of the Fab LM609/α_Vβ₃ integrin complex determined by single particle EM.

(A–B) Two orthogonal views of a random conical tilt 3D reconstruction featuring an α_Vβ₃ integrin activated state. (C–D) Corresponding views related to (A–B) showing the fit of the pseudo-atomic model obtained with Rosetta (ribbon) into the reconstruction (transparent surface). The inset included below depicts the associated 2D class average and a few raw particles (low-pass filtered to 20 Å resolution) used for the RCT reconstruction of the integrin/LM609 extended-state. (E–F) Two orthogonal views of a random conical tilt 3D reconstruction featuring an α_Vβ₃ integrin bent state. (G–H) Corresponding views related to (E–F) showing the fit of the pseudo-atomic model obtained with Rosetta (ribbon) into the reconstruction (transparent surface). The inset included below depicts the associated 2D class average and a few raw particles (low-pass filtered to 20 Å resolution) used for the RCT reconstruction of the integrin/LM609 bent-state. (I) Ribbon diagram of the Fab LM609 bound to the integrin headpiece. Only the β-propeller of the α_V subunit and the βI domain of the β₃ subunit are shown in surface representation colored by electrostatic potential. (J) Corresponding view related to (I) rotated by 70°. The approximate epitope of the LM609 Fab is indicated with black dashed lines and features a pronounced negative electrostatic potential. LM609 is represented as yellow and orange ribbons corresponding to the heavy and light chains, respectively. α_Vβ₃ is represented as fuchsia (α_V) and light blue (β₃) ribbons in panels (C–D) and (G–H).