Ultrastructural localization of contractile protein (Thrombosthenin) in human platelets using an unlabeled antibodyperoxidase staining technique

Soluble hsorserad isis peroxidase-antihiorseradisis peroxidase (rabbit) complex was used to localize tine actomyosin-hike contractile protein, tisrombosthsenin, in boths intact human platelets (Epon-embedded) and ultratisin sections (meth-acrylate-embedded). Antibody staining of ultrathsin sections showed the presence of mennbrane-associated arid cy toplasmic thirombosthenin. Antibody staining of intact cells shsowed that membrane-associated thrombostisenin was localized, at least in part, in use exterior, “fluffy ” coat of the platelet. Even after prolonged fixations and/or incubation with the various antisera, we were unable to demon-strate antibody penetrations of intact, fixed platelets. Brief treatment withs Pronase removed thse surface-localized proteinaceous material and completely abolishsed all antibody staining. The unique ability of l)latelets to adhere to one ansother under the influence of certain physio-logic stimuli forms the basis of the ability for these cells to maintains normal hemostasis. Plate