Association of factor V activity with membranous vesicles released from human platelets: requirement for platelet stimulation.
The membrane-associated factor V-like activity (platelet factor 1, PF1) and the phospholipid-like catalytic surface activity (platelet factor 3, PF3) were studied in human platelets from normal and two factor V-deficient donors. Collagen stimulation or mechanical disruption of gel-filtered platelets was necessary for the expression of significant amounts of PF1 and PF3. Stimulation was also necessary for the uptake of factor V or Va by PF1-deficient platelets from the factor V-deficient donors. The activity of PF1 was also generated by association of factor V or Va with membrane-rich fractions obtained by gel filtration of the supernatant from collagen-stimulated or frozen-thawed PF1-deficient platelets. The amount of PF1 obtained by such all-or-none binding experiments was directly proportional to the amount of PF3 already expressed in the platelet preparation. These data have been summarized in terms of a hypothesis which views PF1 and PF3 to be activities associated with membranous vesicles released from platelets only after stimulation.
D001779:Blood Coagulation Factors / Q000032:analysis / Q000502:physiology*; D001792:Blood Platelets / Q000502:physiology*; D005165:Factor V / Q000502:physiology*; D005166:Factor V Deficiency / Q000097:blood / Q000503:physiopathology*; D006801:Humans; D066298:In Vitro Techniques; D010977:Platelet Factor 3 / Q000032:analysis / Q000502:physiology*
D001779:Blood Coagulation Factors; D010977:Platelet Factor 3; C031546:platelet factor 1; D005165:Factor V