Shielding of the A1 domain by the D′D3 domains of von Willebrand factor modulates its interaction with platelet glycoprotein Ib-IX-V
Shielding of the A1 domain by the D′D3 domains of von Willebrand factor modulates its interaction with platelet glycoprotein Ib-IX-V
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DOI：
10.1074/jbc.m513314200
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发表时间：
2006-02-24
影响因子：
4.8
通讯作者：
Deckmyn, H
中科院分区：
文献类型：
--
作者：
Ulrichts, H;Udvardy, MS;Deckmyn, H
可溶性血管性血友病因子（VWF）对血小板糖蛋白（GP）Ib α具有低亲和力，需要固定化和/或高剪切应力才能使其A1结构域与受体结合。先前描述的抗VWF单克隆抗体1C 1 E7增强VWF/GPIb α结合并识别N-末端D ′ D3结构域中氨基酸764-1035区域中的表位。在这项研究中，我们证明了D 'D3区负性调节VWF/GPIb-IX-V相互作用;（i）VWF中D ′ D3区的缺失增强了与GPIb α的结合，表明该区域的抑制作用，（ii）分离的D ′ D3区抑制缺乏该区域的VWF缺失突变体的GPIb α相互作用，表明分子内相互作用限制了A1结构域的可接近性，（iii）使用一组抗-VWF单克隆抗体，我们接下来显示D ′ D3区与可溶性VWF中的A1结构域紧密接近，但当VWF被固定时不如此;（iv）破坏1C 1 E7的表位导致突变VWF，其对GPIb α的亲和力增加。我们的研究结果支持一个模型的结构域易位的VWF，允许与GPIb α的相互作用。所提出的D 'D3区域对A1结构域的屏蔽相互作用然后被VWF固定化破坏。
Soluble von Willebrand factor (VWF) has a low affinity for platelet glycoprotein (GP) Ib alpha 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/GPIb alpha 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 GPIb alpha, suggesting an inhibitory role for this region, (ii) the isolated D'D3 region inhibited the GPIb alpha 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 GPIb alpha. Our results support a model of domain translocation in VWF that allows interaction with GPIb alpha. The suggested shielding interaction of the A1 domain by the D'D3 region then becomes disrupted by VWF immobilization.