von Willebrand Factor (vWF) is a large plasma glycoprotein which is required for platelets to recognize and bind to damaged endothelial surfaces. Bovine vWF binds directly to human platelets in a manner which is a model for the interaction of human vWF with platelets on subendothelial surfaces. The goals of the project are: (a) to identify the regions of the vWf molecule which are responsible for its binding to platelets, to collagen, and to glycosaminoglycans, (b) to identify the platelet receptor for vWF and determine the mechanism by which vWF binds to platelets, and (c) to describe the effects of vWF binding on the metabolic responses of the platelets, and, conversely, the effects of other agonists on platelet responsiveness to vWF. The functional domains on the vWF molecule will be identified and characterized by proteolytic fragmentation of the vWF, by chemical and enzymatic modification of vWF, and by use of monoclonal antibodies to vWF. The platelet receptor for vWF will be isolated by affinity chromatography and will also be identified in situ by photoaffinity labeling. Platelet responsiveness will be studied by measuring vWF binding, aggregation responses, shape change and the platelet release reaction. Alterations in platelet protein labeling will be monitored and the distribution of receptors on activated and non-activated platelets will be visualized by electron microscopy with gold-conjugated specific probes for the receptors. These studies should provide a better understanding of the basic mechanisms underlying platelet recognition of sites of damage in blood vessels. They may suggest new ways to deal with the thrombotic complications associated with diseased or damaged blood vessels or with artificial surfaces such as prosthetic heart valves, dialysis membranes, or vascular prostheses.

National Institute of Health (NIH)
National Heart, Lung, and Blood Institute (NHLBI)
Research Project (R01)
Project #
Application #
Study Section
Hematology Subcommittee 2 (HEM)
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Temple University
Schools of Medicine
United States
Zip Code
Sinha, D; Bakhshi, M R; Vora, R K et al. (1996) Engineering DNA and protein chimeras utilizing coding sequences of restriction sites. Anal Biochem 238:205-8
Bakhshi, M R; Sinha, D; Vora, R K et al. (1996) Primary binding domain of bovine von Willebrand factor fragment expressed in E. coli. Thromb Haemost 75:196-202
Janel, N; Schwachtgen, J L; Bakhshi, M R et al. (1995) Comparison of the 5'-flanking sequences of the human and bovine von Willebrand factor-encoding genes reveals alternation of highly homologous domains with species-specific Alu-type repeats. Gene 167:291-5
Sinha, D; Yang, X; Emig, F et al. (1994) Isolation and characterization of two protease inhibitors from bovine plasma. J Biochem 115:387-91
Sinha, D; Bakhshi, M; Vora, R (1994) Ligand binding assays with recombinant proteins refolded on an affinity matrix. Biotechniques 17:509-12, 514
Sinha, D; Bakhshi, M; Kunapuli, S et al. (1994) ASP514 within the A1 domain of bovine von Willebrand factor is required for interaction with platelet glycoprotein Ib. Biochem Biophys Res Commun 203:881-8
Peng, M; Lu, W; Beviglia, L et al. (1993) Echicetin: a snake venom protein that inhibits binding of von Willebrand factor and alboaggregins to platelet glycoprotein Ib. Blood 81:2321-8
Bakhshi, M R; Myers, J C; Howard, P S et al. (1992) Sequencing of the primary adhesion domain of bovine von Willebrand factor. Biochim Biophys Acta 1132:325-8
Peng, M; Lu, W; Kirby, E P (1992) Characterization of three alboaggregins purified from Trimeresurus albolabris venom. Thromb Haemost 67:702-7
Peng, M; Lu, W; Kirby, E P (1991) Alboaggregin-B: a new platelet agonist that binds to platelet membrane glycoprotein Ib. Biochemistry 30:11529-36

Showing the most recent 10 out of 16 publications