Characterization of monoclonal antibodies to human platelet myosin that recognize highly conserved epitopes within the 50 kDa fragment of myosin subfragment-1.

Three monoclonal antibodies directed against human platelet myosin heavy chains (MCH) that recognize homologous sequences contained within the functionally active subfragment-1, in platelet and rabbit skeletal muscle myosin were studied. These antibodies are distinguished by their affinities to different myosins and their differential effect on various ATPase activities. Epitope mapping was accomplished by analyzing antibody binding to proteolytic peptides of myosin head subfragment-1 under various experimental conditions. The epitopes recognized by these anti-human platelet MHC monoclonal antibodies reside within a small region of the 50 kDa fragment, beginning 9 kDa from its C-terminus and extending a stretch of 6 kDa towards the N-terminus. These epitopes lie between residues 535-586, and are contained within a highly conserved area of myosin heavy chain.