Title: Shielding of the A1 domain by the D'D3 domains of von Willebrand factor modulates its interaction with platelet glycoprotein Ib-IX-V
Authors: Ulrichts, Hans ×
Udvardy, Miklós
Lenting, Peter J
Pareyn, Inge
Vandeputte, Nele
Vanhoorelbeke, Karen
Deckmyn, Hans #
Issue Date: 24-Jan-2006
Series Title: Journal of Biological Chemistry vol:281 issue:8 pages:4699-4707
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.
ISSN: 0021-9258
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Interdisciplinary Research Facility Life Sciences, Campus Kulak Kortrijk
Chemistry, Campus Kulak Kortrijk
× corresponding author
# (joint) last author

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