A diagram showing large conformational change in the integrin CD11b/CD18 that is expected upon integrin activation. The integrin exists primarily in a bent, low-affinity conformation on the surface of circulating leukocytes under basal conditions. Upon activation, the dimer changes conformation and adopts a more upright, active, high-affinity form that is bound to large, extracellular ligands with high affinity at the MIDAS site (shown with a red sphere representing a metal ion at the MIDAS site). Relative locations of each of the three CD11b mutations encoded by the comment ITGAM variants are also shown on the diagram.