The effect of antibodies to human platelet membrane and cytoplasmic myosins on myosin ATPase activity and platelet aggregation.
Myosins were purified from the membrane fraction and the cytoplasm of human platelets. Polyclonal antibodies to the purified myosins were induced in rabbits. Their effects on the ATPase activity of the purified myosins as well as on the process of platelet aggregation were studied. A strong cross reactivity was found between the two myosins and their respective antibodies by the ELISA technique. It was found that the antibodies preferentially bind to the "head" segment of the myosins, since purified myosin "rod" reacted only weakly with the two kinds of antibodies. The two antimyosin antibodies strongly inhibited the K+(EDTA) ATPase activity of both myosins, as well as the activity of the isolated myosin "heads". The amount of antimembrane myosin antibody required to inhibit the above enzymatic activity was smaller than that of the anticytoplasmatic myosin antibody. Similar results were observed with F(ab)2 fragments of the two kinds of antibodies. No effect of these antibodies or their F(ab)2 fragments was observed on platelet aggregation induced by various agonists, although their inhibitory effect on the platelet myosin ATPase activity was strong.
Peleg
I
I
Eldor
A
A
Muhlrad
A
A
Groschel-Stewart
U
U
Kahane
I
I
D000251:Adenosine Triphosphatases / Q000276:immunology*; D000906:Antibodies / Q000276:immunology; D000941:Antigens / Q000276:immunology; D001792:Blood Platelets / Q000276:immunology* / Q000378:metabolism; D002462:Cell Membrane / Q000276:immunology; D003429:Cross Reactions; D003593:Cytoplasm / Q000276:immunology; D006801:Humans; D007120:Immunochemistry; D007140:Immunoglobulin Fab Fragments / Q000276:immunology; D066298:In Vitro Techniques; D009218:Myosins / Q000276:immunology*; D010974:Platelet Aggregation
D000906:Antibodies; D000941:Antigens; D007140:Immunoglobulin Fab Fragments; D000251:Adenosine Triphosphatases; D009218:Myosins