The p40 phox and p47 phox PX Domains of NADPH Oxidase Target Cell Membranes via Direct and Indirect Recruitment by Phosphoinositides*-猫眼课题宝

NADPH 氧化酶靶细胞膜的 p40 phox 和 p47 phox PX 结构域通过磷酸肌醇直接和间接招募*

DOI：

发表时间：

2002

期刊：

Journal of Biological Chemistry

影响因子：

4.8

通讯作者：

中科院分区：

生物学2区

文献类型：

作者：

Yong Zhan;J. Virbasius;Xi Song;Darcy P. Pomerleau;G. Zhou

Phox同源结构域（PX）与磷酸肌醇结合，部分PX结构域在体内可定位于核内体。在这里，我们显示的数据支持的结论，p40 phox PX结构域结合磷脂酰肌醇3-磷酸特异性在体外和本地化的完整细胞内体。此外，其Y 59 A/L 65 Q突变体在体外对磷脂酰肌醇3-磷酸的亲和力降低，不能将EGFP-p40-PX靶向到内体。然而，与已发表的结果不同，我们发现p47 phox PX结构域在体外与许多磷脂酰肌醇3，4，5-三磷酸的亲和力略高。此外，我们首次表明，胰岛素样生长因子-1刺激COS细胞后，p47 phox PX结构域定位于质膜，这种亚细胞定位依赖于PI 3-激酶活性。出乎意料的是，其R42 Q突变体在体外失去了磷酸肌醇结合能力，但仍然可以将EGFP-p47-PX靶向质膜。我们的数据表明，p47 phox PX结构域的易位到质膜的过程中确实涉及3′-磷酸肌醇，但磷酸肌醇结合p47 phox PX结构域不足以将其募集到质膜。因此，p40 phox和p47 phox PX结构域可以通过磷酸肌醇直接或间接募集靶向亚细胞膜，而两者都在磷脂酰肌醇3-激酶活性的控制下。

The Phox homology (PX) domain has recently been reported to bind to phosphoinositides, and some PX domains can localize to endosomes in vivo. Here we show data to support the conclusion that the p40 phox PX domain binds to phosphatidylinositol 3-phosphate specifically in vitro and localizes to endosomes in intact cells. In addition, its Y59A/L65Q mutant, which has decreased affinity for phosphatidylinositol 3-phosphate in vitro, fails to target EGFP-p40-PX to endosomes. However, unlike published results, we find that the p47 phox PX domain weakly binds to many phosphoinositides in vitro showing slightly higher affinity for phosphatidylinositol 3,4,5-trisphosphate. Moreover, we show for the first time that upon insulin-like growth factor-1 stimulation of COS cells, the p47 phox PX domain is localized to the plasma membrane, and this subcellular localization is dependent on PI 3-kinase activity. Unexpectedly, its R42Q mutant that loses in vitrophosphoinositide-binding ability can still target EGFP-p47-PX to the plasma membrane. Our data suggest that the translocation of p47 phox PX domain to the plasma membrane does involve 3′-phosphoinositide(s) in the process, but the phosphoinositide-binding of p47 phox PX domain is not sufficient to recruit it to the plasma membrane. Therefore, the p40 phox and p47 phox PX domains can target subcellular membranes via direct or indirect recruitment by phosphoinositides, while both are under the control of phosphatidylinositol 3-kinase activity.

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