Immunochemical characterization of the transglutaminase-catalyzed polymer of activated platelets

Platelet proteins which contribute to transglutaminase-catalyzed polymer formation in activated platelets were identified by an immunochemical approach using the Western blot technique. The cross-linked polymer was purified from thrombin- or Ca2+-ionophore A23187-activated platelets by a sucrose density gradient procedure in reducing conditions and in the presence of a non-ionic detergent. Following transblotting of non-crosslinked platelet proteins from a Laemmli-type gel onto nitrocellulose, the platelet protein "lanes" were incubated with unabsorbed antibodies, or antibodies absorbed with purified polymer. Antibodies to native whole platelets as well as specific antibodies were used. The results show that myosin, actin, glycoproteins IIb, IIIa, and tubulin are present in the polymer.