Fine structural localization of adenosine triphosphatase in human platelets and other blood cells.

By JAMES G. WHITE AND WILLIAM Knivrr T lIE UTILIZATION of adenosine triphosphate ( ATP) by human platelets during clot formation and retraction is important to the functioning of these cells in clotting physiology.’ 2 Recent developments in histochemical and electron microscopic methods have permitted identification of enzymes hydrolyzing ATP at the fine structural level.t We have applied these combined technics to the localization of platelet adenosine triphosphatase ( ATPase). Enzyme activity was found on platelet surface membranes and in intraplatelet organdIes. In the course of this investigation, ATPase activity was also observed in other blood cells. Enzyme reaction product occurred on red cell and lymphocyte surface membranes, and in lymphocyte mitochondria and nucleoli.