Fig. 1.

Overall integrin conformational states. a–c Talin-binding integrins. d–f Band 4.1-binding integrin αVβ8. d Population of the bent-closed conformation is very low in αVβ8^14–16, whereas this is by far the most populous state on cell surfaces in typical integrins (a)⁹. e The extended-closed conformation is by far the most populous αVβ8 conformation, at least in solution^14–16. f αVβ8 does not exhibit a ligand-stabilized extended-open conformation like typical integrins (c). However, ligand binding induces movement of the α1-helix (and SDL1, which includes the N-terminal portion of the α1-helix and its preceding loop) toward the open state of the βI domain. The β6-α7 loop in the βI domain is unengaged with the α7-helix, enabling opening of the βI domain to occur in the absence of hybrid domain swing-out.