Cytochrome b558 is the only membrane component of the phagocyte O2- NADPH oxidase. The O2- production by the oxidase reconstituted in vitro with the crude membrane fraction is enhanced several-fold by addition of FAD, whereas that with the partially purified cytochrome is completely dependent on exogenous FAD, suggesting that FAD acts through the membrane component, cytochrome b558. The alignments of the amino acid sequence of the large subunit of the cytochrome (gp91-phox) with those of previously characterized flavoproteins reveal that the middle and C-terminal portions of gp91-phox are likely to be FAD- and NADPHbinding domains, respectively. Cytochrome b558, thus, appears to be a flavoprotein with an NADPH-binding site, of the NADPH oxidase.
|Number of pages||8|
|Journal||Biochemical and Biophysical Research Communications|
|Publication status||Published - Aug 14 1992|
All Science Journal Classification (ASJC) codes
- Molecular Biology
- Cell Biology