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Adhesive Properties of the Isolated Amino-Terminal Domain of Platelet Glycoprotein Ibα in a Flow Field
Patrizia Marchese, Enrique Saldívar, Jerry Ware and Zaverio M. Ruggeri
Proceedings of the National Academy of Sciences of the United States of America
Vol. 96, No. 14 (Jul. 16, 1999), pp. 7837-7842
Published by: National Academy of Sciences
Stable URL: http://www.jstor.org/stable/48387
Page Count: 6
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We have examined the interaction between the amino-terminal domain of platelet glycoprotein (GP) Ibα and immobilized von Willebrand Factor (vWF) under flow conditions in the absence of other components of the GP Ib-IX-V complex. Latex beads were coated with a recombinant fragment containing GP Ibα residues 1-302, either with normal sequence or with the single G233V substitution that causes enhanced affinity for plasma vWF in platelet-type pseudo-von-Willebrand disease. Beads coated with native fragment adhered to vWF in a manner comparable to platelets, showing surface translocation that reflected the transient nature of the bonds formed. Thus, the GP Ibα extracellular domain is necessary and sufficient for interacting with vWF under high shear stress. Beads coated with the mutated fragment became tethered to vWF in greater number and had lower velocity of translocation than beads coated with the normal counterpart, suggesting that the G233V mutation lowers the rate of bond dissociation. Our findings define an approach for studying the biomechanical properties of the GP Ibα -WF bond and suggest that this interaction is tightly regulated to allow rapid binding at sites of vascular injury, while permitting the concurrent presence of receptor and ligand in the circulation.
Proceedings of the National Academy of Sciences of the United States of America © 1999 National Academy of Sciences