Role of Src homology 3 domains in assembly and activation of the phagocyte NADPH oxidase

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作者：

H Sumimoto，Y Kage，H Nunoi，H Sasaki，T Nose，Y Fukumaki，M Ohno，S Minakami，K Takeshige

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摘要：

The phagocyte NADPH oxidase, dormant in resting cells, is activated during phagocytosis to produce superoxide, a precursor of microbicidal oxidants. The activated oxidase is a complex of membrane-integrated cytochrome b558, composed of 91-kDa (gp91phox) and 22-kDa (p22phox) subunits, and two cytosolic factors (p47phoxand p67phox), each containing two Src homology 3 (SH3) domains. Here we show that the region of the tandem SH3 domains of p47phox(p47-SH3) expressed as a glutathione S-transferase fusion protein inhibits the superoxide production in a cell-free system, indicating involvement of the domains in the activation. Furthermore, we find that arachidonic acid and sodium dodecyl sulfate, activators of the oxidase in vitro, cause exposure of p47-SH3, which has probably been masked by the C-terminal region of this protein in a resting state. The unmasking of p47-SH3 appears to play a crucial role in the assembly of the oxidase components, because p47-SH3 binds to both p22phoxand p67phoxbut fails to interact with a mutant p22phoxcarrying a Pro-156 → Gln substitution in a proline-rich region, which has been found in a patient with chronic granulomatous disease. Based on the observations, we propose a signal-transducing mechanism whereby normally inaccessible SH3 domains become exposed upon activation to interact with their target proteins.

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关键词：

Biochemistry Superoxide Cytochrome b558 Proline-Rich Region Chronic Granulomatous Disease

DOI：

10.1073/pnas.91.12.5345

被引量：

727

年份：

1994