Fibronectin (green and yellow) can bind to a bent integrin (blue and red).

A bent integrin still has room for its ligand, according to Adair et al. on page 1109. Integrin activation by internal signals may therefore not depend on the protein assuming a more extended conformation.

To prevent unregulated adhesion, most integrins are expressed in an inactive form. EM and crystal structures showed that the extracellular domain of the integrin αVβ3 without its ligand can assume a bent conformation. 2D EM reconstructions of the same domain in the presence of a small peptide suggested that the bound form, in contrast, was extended. These results supported a switchblade model, in which the binding of cytoplasmic signals initiates the movement of several intra- and extracellular domains that opens and activates the integrin by exposing its ligand-binding site.

But Adair et al. suggest that such large-scale...

The Rockefeller University Press
2005
The Rockefeller University Press
2005
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