ULTRASTRUCTURAL LOCALIZATION OF Mg++-DEPENDENT DINITROPHENOL-STIMULATED ADENOSINE TRIPHOSPHATASE IN HUMAN BLOOD PLATELETS

Abstract
Fine structural localization of adenosine triphosphatase activity was studied in human platelets briefly fixed in cold formol calcium and then incubated in lead medium with added dinitrophenol. Under these conditions, the Mg++-dependent dinitrophenol-stimulated adenosine triphosphatase of platelet mitochondria was demonstrated, but neither granules nor plasma membrane showed enzyme activity.