PMID:16373331
| Citation |
Ulrichts, H, Udvardy, M, Lenting, PJ, Pareyn, I, Vandeputte, N, Vanhoorelbeke, K and Deckmyn, H (2006) Shielding of the A1 domain by the D'D3 domains of von Willebrand factor modulates its interaction with platelet glycoprotein Ib-IX-V. J. Biol. Chem. 281:4699-707 |
|---|---|
| Abstract |
Soluble von Willebrand factor (VWF) has a low affinity for platelet glycoprotein (GP) Ibalpha and needs immobilization and/or high shear stress to enable binding of its A1 domain to the receptor. The previously described anti-VWF monoclonal antibody 1C1E7 enhances VWF/GPIbalpha binding and recognizes an epitope in the amino acids 764-1035 region in the N-terminal D'D3 domains. In this study we demonstrated that the D'D3 region negatively modulates the VWF/GPIb-IX-V interaction; (i) deletion of the D'D3 region in VWF augmented binding to GPIbalpha, suggesting an inhibitory role for this region, (ii) the isolated D'D3 region inhibited the GPIbalpha interaction of a VWF deletion mutant lacking this region, indicating that intramolecular interactions limit the accessibility of the A1 domain, (iii) using a panel of anti-VWF monoclonal antibodies, we next showed that the D'D3 region is in close proximity with the A1 domain in soluble VWF but not when VWF was immobilized; (iv) destroying the epitope of 1C1E7 resulted in a mutant VWF with an increased affinity for GPIbalpha. Our results support a model of domain translocation in VWF that allows interaction with GPIbalpha. The suggested shielding interaction of the A1 domain by the D'D3 region then becomes disrupted by VWF immobilization. |
| Links |
PubMed Online version:10.1074/jbc.M513314200 |
| Keywords |
Animals; Antibodies, Monoclonal/chemistry; Blood Platelets/metabolism; Collagen Type III/chemistry; Cricetinae; Crotalid Venoms/chemistry; DNA Primers/chemistry; Epitope Mapping; Epitopes/chemistry; Escherichia coli/metabolism; Gene Deletion; Humans; Hybridomas/metabolism; Kidney/metabolism; Mutation; Plasmids/metabolism; Platelet Glycoprotein GPIb-IX Complex/chemistry; Protein Binding; Protein Structure, Tertiary; Protein Transport; RNA/metabolism; Recombinant Fusion Proteins/chemistry; Recombinant Proteins/chemistry; Ristocetin/chemistry; Swine; Time Factors; von Willebrand Factor/chemistry |
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