Locking the β3 integrin I-like domain into high and low affinity conformations with disulfides

Citation:

Luo, B.-H., Takagi, J. & Springer, T.A. Locking the β3 integrin I-like domain into high and low affinity conformations with disulfides. J. Biol. Chem. 279, 11, 10215-10221 (2004).
Luo_2004_16236.pdf283 KB

Abstract:

Although integrin alpha subunit I domains exist in multiple conformations, it is controversial whether integrin beta subunit I-like domains undergo structurally analogous movements of the alpha7-helix that are linked to affinity for ligand. Disulfide bonds were introduced into the beta(3) integrin I-like domain to lock its beta6-alpha7 loop and alpha7-helix in two distinct conformations. Soluble ligand binding, ligand mimetic mAb binding and cell adhesion studies showed that disulfide-bonded receptor alpha(IIb)beta(3)(T329C/A347C) was locked in a low affinity state, and dithiothreitol treatment restored the capability of being activated to high affinity binding; by contrast, disulfide-bonded alpha(IIb)beta(3)(V332C/M335C) was locked in a high affinity state. The results suggest that activation of the beta subunit I-like domain is analogous to that of the alpha subunit I domain, i.e. that axial movement in the C-terminal direction of the alpha7-helix is linked to rearrangement of the I-like domain metal ion-dependent adhesion site into a high affinity conformation.

Notes:

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Last updated on 09/30/2015