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Measurement of the binding forces between von Willebrand factor and variants of platelet glycoprotein Ibα using optical tweezers
Author(s) -
Arya Maneesh,
López José A.,
Romo Gabriel M.,
Dong JingFei,
McIntire Larry V.,
Moake Joel L.,
Anvari Bahman
Publication year - 2002
Publication title -
lasers in surgery and medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 112
eISSN - 1096-9101
pISSN - 0196-8092
DOI - 10.1002/lsm.10044
Subject(s) - von willebrand factor , chinese hamster ovary cell , platelet , von willebrand disease , chemistry , ristocetin , glycoprotein , platelet membrane glycoprotein , microbiology and biotechnology , glycoprotein ib , leucine rich repeat , receptor , biology , biochemistry , immunology
Background and Objective Thrombus formation is initiated by adhesion of the platelet receptor, glycoprotein (GP) Ib‐IX‐V complex, to its adhesive ligand, von Willebrand factor (vWf), in the subendothelium or plasma. The vWf‐binding domain of GP Ib‐IX‐V is in the GP Ibα subunit of the complex and contains a leucine‐rich repeat region. The adhesion of different leucine‐rich repeats was studied using optical tweezers in order to determine which ones were critical for the vWf/GP Ibα interaction. Study Design/Materials and Methods Canine GP Ibα does not normally bind to human vWf, and thus canine‐human GP Ibα chimeras were constructed by sequentially replacing human GP Ibα structural regions with their canine counterparts. Chinese hamster ovary (CHO) cells, which are frequently used to express platelet GP complexes, were transfected with the chimeric proteins. Optical tweezers (λ = 830 nm) were used to investigate bond strengths between vWf and different GP Ibα canine‐human chimeras. Since vWf does not bind GP Ibα without high shear stress, the compounds botrocetin and ristocetin were used to induce binding between human vWf and the chimeras. Results All human‐canine GP Ibα chimeras bound to vWf in the presence of botrocetin. Replacement of the N‐terminal flanking sequence and the first leucine‐rich repeat resulted in lower GP Ibα/vWf bond strengths than the wild‐type human GP Ibα/vWf bond strength ( P < 0.05). Chimeras lacking the second leucine‐rich repeat did not adhere to vWf with ristocetin acting as modulator. Conclusion The N‐terminal flanking sequence and the first leucine‐rich repeat of GP Ibα were found to be important but not necessary for GP Ibα to adhere to vWf. The second leucine‐rich repeat was found to be critical for GP Ibα to bind vWf and could potentially be used in the development of a novel recombinant anti‐thrombotic drugs. Lasers Surg. Med. 30:306–312, 2002. © 2002 Wiley‐Liss, Inc.