抄録
Active NADPH oxidase of neutrophils is found on the membrane as an enzyme complex, composed of membrane integrated cytochrome b558 (gp91 and p22 subunits), and two cytosolic factors (p47 and p67) . Recently, we radioactively identified a third cytosolic factor, p40, as a molecule which associates with p67. However, there is no evidence to functionally relate it to the NADPH oxidase system.
In this study, we raised antibodies against either the C-or N-terminal polypeptide of p40 as well as against the C-terminal polypeptide of p67 to examine the mode of interaction between p40 and p67 in a complex unit. The antibody against the C-terminus of p67 was able to coimmunoprecipitate p40 in conjunction with p67. Interestingly, however, antibody against the C-terminus of p40 completely dissociated the p67 molecule from the p40-p67 complex unit, despite their tight association, whereas that against the N-terminus of p40 had absolutely no dissociation effect. Similar results were found regarding their effects on the O-2-generating ability of cytosol potentiated with myristic acid in a cell free activation system, i.e., its inhibition with the antibody for the C-terminus but not with that for the N-terminus of p40.
These results are first demonstration that p40 is virtually involved in the activation process of NADPH oxidase through its C-terminal, but not its N-terminal, association with p67.
