Activation of rabbit brain microsomal (Na+ plus K+)-dependent ATPase by a leukocytic product

The properties of a (Na+ plus K+)-dependent ATPase (ATP phosphohydrolase, EC 3.6.1.3) activator contained in leukocytic extracts was investigated. Intact polymorphonuclear leukocytes release the activator in a time- and temperature-dependent process. It is non-dialyzable through cellophane; inactivated by protease, trypsin, or phenol; contains essential sulfhydryl groups; and is heat and acid labile. Treatment of ATPase with the activator and subsequent removable of the activator from mixtures did not reverse the ATPase activation.