title: Multimeric structure of platelet factor VIII/von Willebrand factor: the presence of larger multimers and their reassociation with thrombin-stimulated platelets.
abstract: The multimeric structure of platelet factor VIII/von Willebrand factor (FVIII/vWF) in cell extracts and in collagen and thrombin releasates has been analyzed by SDS polyacrylamide gel electrophoresis followed by detection with 125I-anti-FVIII/vWF. Platelets contained larger multimers than those normally present in plasma. When secreted FVIII/vWF was analyzed, all platelets. In contrast, in thrombin releasates the larger multimers were lost in a manner dependent on divalent cations, time, and thrombin dose. This loss could not be accounted for by modification of FVIII/vWF by thrombin or platelet enzymes since no effect of thrombin on the multimeric structure of FVIII/vWF in the absence of platelets or in the presence of platelet lysates was observed. Large multimers of 125I-labeled purified FVIII/vWF underwent divalent cation-dependent association with platelets in the presence of thrombin, indicating that the loss of FVIII/vWF from thrombin releasates was due to reassociation with the platelet. These studies show a structural difference between platelet and plasma FVIII/vWF that suggests a specific role for platelet FVIII/vWF in hemostasis.
mesh_terms: D001779:Blood Coagulation Factors / Q000502:physiology*; D001792:Blood Platelets / Q000187:drug effects / Q000502:physiology; D004587:Electrophoresis, Agar Gel; D006801:Humans; D007122:Immunoelectrophoresis; D012967:Sodium Dodecyl Sulfate; D013329:Structure-Activity Relationship; D013917:Thrombin / Q000494:pharmacology; D014841:von Willebrand Factor / Q000302:isolation & purification / Q000502:physiology*
chemical_list: D001779:Blood Coagulation Factors; D014841:von Willebrand Factor; D012967:Sodium Dodecyl Sulfate; D013917:Thrombin