Figure 1.

Integrin exists in a conformational equilibrium of four major conformers. (A) Nondenaturating native gel electrophoresis was used to assess the integration of integrin into nanodiscs. When integrin and nanodiscs were incubated together, the integrin band spatially relocated on the gel (arrowhead) without splitting. (B) Distribution of integrin conformers in the absence and presence of nanodiscs, talin head domain, and RGD peptide. In both conditions, four conformations are observed: bent (red), first intermediate (green), second intermediate (yellow), and upright (blue). The standard deviation for all percentages is between 1% and 2% (Table 1). (C) Surface representations of the 3D reconstructions corresponding to the colors in the pie charts are shown. The contour level was chosen to account for integrin’s molecular weight. All four images are at the same magnification. The light-gray strip indicates the approximate membrane position as suggested by reconstructions of integrins bound to nanodiscs. Scale bar, 10 nm. To see this figure in color, go online.