NADPH: nitroblue tetrazolium reductase found in plasma membrane of human neutrophil

After phorbol 12-myristate 13-acetate (PMA) stimulation the increase of NADPH:nitroblue tetrazolium reductase activity in the plasma membrane almost corresponded with the stimulated activity of respiratory burst oxidase. Solubilization of plasma membranes from PMA-activated neutrophils with n-octyl glucoside resulted in high recoveries of the two enzymatic activities. When solubilized plasma membrane was subjected to non-denaturing polyacrylamide gel electrophoresis in the presence of 35 mM n-octyl glucoside, we could see three major bands stained with NADPH-dependent nitroblue reductase activity giving molecular masses of approx. 95, 45 and 40 kDa, respectively. Activity was specific for NADPH but not for NADH. These bands also stained weakly in the plasma membranes obtained from resting cells. The activities for NADPH oxidase and nitroblue tetrazolium reductase were found to elute as a very similar protein peak on an anion-exchange HPLC, at about 0.32 M KCl. This elution peak also contains 45 and 40 kDa proteins showing NADPH:nitroblue tetrazolium reductase activity.