摘要：

The neutrophil oxidase is a multi-component complex composed of -bound and cytosolic proteins. During activation, cytosolic proteins (phox), (phox), , and possibly (phox) translocate to the and associate with to form the active -generating system. To further investigate the role of (phox) in this complex assembly process, experiments were performed to identify possible regions of interaction between (phox) and other oxidase proteins. Using random sequence phage-display library analysis of (phox), we identified a novel region in (phox) encompassing residues 323-332 and a previously identified SH3 domain encompassing (phox) residues 361-370 as (phox) sites. Synthetic mimicking (phox) residues 323-332 inhibited the (phox)-(phox) interaction in an affinity assay; however, mimicking flanking regions were inactive. Surprisingly, this same region of (phox) was found previously to represent a site of interaction for (DeLeo, F. R., Nauseef, W. M., Jesaitis, A. J., Burritt, J. B., Clark, R. A., and Quinn, M. T.(1995) J. Biol. Chem. 270, 26246-26251), and this observation was confirmed in the present report using two different in vitro assays that were not evaluated previously. Using affinity assays, we also found that (phox) and competed for to (phox)after activation, suggesting that prior to full oxidase assembly the 323-332 region of (phox) is associated with (phox) and at some point in the activation process is transferred to . Thus, taken together our data demonstrate that both (phox) and utilize a common site in (phox), presumably at distinct stages during the activation process, and this (phox) region plays a key role in regulating oxidase assembly.

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