Title: Characterization of the binding of human tissue-type plasminogen activator to platelets
Authors: Vaughan, D E ×
Mendelsohn, M E
Declerck, Paul
Van Houtte, E
Collen, Desire
Loscalzo, J #
Issue Date: Sep-1989
Series Title: Journal of Biological Chemistry vol:264 issue:27 pages:15869-74
Abstract: Cell surface binding sites for the constituent proteins of the fibrinolytic system may play a role in the localization and regulation of fibrinolysis. In the present study, specific binding of recombinant human tissue-type plasminogen activator (rt-PA) to human blood platelets was identified and characterized. 125I-labeled rt-PA was found to bind specifically, saturably, and reversibly to the surface of gel-filtered platelets, reaching equilibrium within 5 min at 22 degrees C. Scatchard analysis revealed a single class of binding sites. Unstimulated platelets bound 120,000 +/- 24,000 (mean +/- S.D.) molecules/platelet with an apparent Kd of 340 +/- 25 nM, whereas thrombin-stimulated platelets bound 290,000 +/- 32,000 molecules/platelet with an apparent Kd of 800 +/- 60 nM. Binding of 0.1 microM 125I-rt-PA was greater than 90% reversible by a 50-fold excess of unlabeled rt-PA. Binding was not inhibited by fibrinogen or single chain urokinase-type plasminogen activator, but plasminogen partially competed for binding of 125I-rt-PA to platelets (up to 40% displacement). These findings indicate that the platelet surface possesses a large number of specific, low affinity binding sites for t-PA and provide further evidence for the role of platelets in localization and regulation of fibrinolysis.
ISSN: 0021-9258
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Molecular and Vascular Biology
Laboratory for Pharmaceutical Biology (-)
× corresponding author
# (joint) last author

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