The deadbolt model of inside-out integrin activation. (A) Surface representation of unliganded α_Vβ₃ in which the βTD (blue), hybrid (yellow), and βA (red) domains are colored and the propeller (P), thigh (T), calf-1 and 2 (C1, C2), and EGF4 (E4) are labeled. The cations at ADMIDAS (magenta) and blade 6 (orange) are visible in this view. (B) Ribbon diagram showing the 2 βTD loops (⋆, blue) that contact βA (red) and the hybrid (yellow) domains. The long CD loop of the βTD contacts the top of the activation-sensitive F/α₇ of βA (colored in green). The ADMIDAS cation links this loop to the top of the α₁ helix in the unliganded state. Parts of the propeller (cyan), hybrid (yellow), and EGF4 (white) are shown. (C) Ribbon diagram of the inactive form of αA from integrin CD11a in complex with the allosteric inhibitor lovastatin (blue) showing the position of this drug in relation to the F/α₇ region (colored in green). The MIDAS ion is in cyan. There is no ADMIDAS in this or other known αA domains.