3NIG

The Closed Headpiece of Integrin IIb 3 and its Complex with an IIb 3 -Specific Antagonist That Does Not Induce Opening

Summary for 3NIG

• Entry DOI: 10.2210/pdb3nig/pdb
• Related: 2VDR 3NID 3NIF
• Descriptor: Integrin alpha-IIb, MAGNESIUM ION, 2-acetamido-2-deoxy-beta-D-glucopyranose, ... (12 entities in total)
• Functional Keywords: integrin, headpiece, alphaiib, beta3, cell adhesion-immune system complex, cell adhesion-blood clotting complex, cell adhesion/blood clotting
• Biological source: Homo sapiens (human); More
• Total number of polymer chains: 8
• Total formula weight: 300994.33

Authors

Zhu, J.H.,Zhu, J.Q.,Springer, T.A. (deposition date: 2010-06-15, release date: 2010-12-22, Last modification date: 2023-09-06)

Primary citation

Zhu, J.,Zhu, J.,Negri, A.,Provasi, D.,Filizola, M.,Coller, B.S.,Springer, T.A.
Closed headpiece of integrin {alpha}IIb{beta}3 and its complex with an {alpha}IIb{beta}3-specific antagonist that does not induce opening.
Blood, 116:5050-5059, 2010

PubMed Abstract: The platelet integrin α(IIb)β(3) is essential for hemostasis and thrombosis through its binding of adhesive plasma proteins. We have determined crystal structures of the α(IIb)β(3) headpiece in the absence of ligand and after soaking in RUC-1, a novel small molecule antagonist. In the absence of ligand, the α(IIb)β(3) headpiece is in a closed conformation, distinct from the open conformation visualized in presence of Arg-Gly-Asp (RGD) antagonists. In contrast to RGD antagonists, RUC-1 binds only to the α(IIb) subunit. Molecular dynamics revealed nearly identical binding. Two species-specific residues, α(IIb) Y190 and α(IIb) D232, in the RUC-1 binding site were confirmed as important by mutagenesis. In sharp contrast to RGD-based antagonists, RUC-1 did not induce α(IIb)β(3) to adopt an open conformation, as determined by gel filtration and dynamic light scattering. These studies provide insights into the factors that regulate integrin headpiece opening, and demonstrate the molecular basis for a novel mechanism of integrin antagonism.

PubMed: 20679525
DOI: 10.1182/blood-2010-04-281154

Experimental method

X-RAY DIFFRACTION (2.25 Å)