Relationships of p40phox with p67phox in the Activation and Expression of the Human Respiratory Burst NADPH Oxidase1.

p40phox of the phagocyte NADPH oxidase forms a complex with p67phox in cytosol, and coincidentally decreases in patients who lack p67phox. Here we investigated the mode of translocation of p40phoxto the membrane, its cytoskeletal localization on activation of the NADPH oxidase, and the dependency of its expression relative to that of p67phox. When human polymorphonuclear leukocytes (PMNs) were stimulated with phorbol myristate acetate (PMA), p40phox was translocated to the membrane along with p67phox, and not was released into the cytosol. Studies with resting PMNs using Triton X-100 revealed the exclusive localization of p67phox in the cytoskeletal fraction. Unexpectedly, however, about half of p40phox, which is deemed to be fully associated with p67phox, was recovered in the non-cytoskeletal fraction. Unlike p47phox association of p40phox with cytoskeleton was not induced by the PMA-stimulation. These results indicate not only that p40phox associates with cytoskeleton via a molecule of p67phox, but also that there are distinct states of p40phox that can be manipulated with Triton X-100. Lastly, Western-blot analysis of hematopoietic cells revealed no correlation between p40phox and p67phox in their protein expressions during cell differentiation, and also that p40phox can be stably present alone in cells, unless in the case of mature PMNs. In this regard, definitive proof was obtained with Epstein-Barr virus-transformed B cells of a p67phox-deficient patient, in which p40phox was normally expressed [ABSTRACT FROM AUTHOR]

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