NOXO1, regulation of lipid binding, localization, and activation of Nox1 by the phox homology (PX) domain
NOXO1, regulation of lipid binding, localization, and activation of Nox1 by the phox homology (PX) domain
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DOI：
10.1074/jbc.m305968200
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发表时间：
2004-02-06
影响因子：
4.8
通讯作者：
Lambeth, JD
中科院分区：
文献类型：
--
作者：
Cheng, GJ;Lambeth, JD
NOXO 1（Nox organizing protein 1）和NOXA 1（Nox activating protein 1）是p47（phox）和p67（phox）的同源物。p47（phox）在吞噬细胞中作为一种必需的组织蛋白发挥作用，在吞噬细胞氧化酶活化期间介导其他调节蛋白的结合，并且其向膜的移位在细胞活化后通过过度磷酸化而触发，这解除了SH 3和PX结构域的自身抑制。NOXO 1缺乏自身抑制区域和存在于p47（phox）中的磷酸化位点。Nox 1、NOXO 1和NOXA 1的共转染在不存在细胞刺激的情况下重建了HEK 293细胞中的ROS（活性氧）产生。NOXO 1与磷脂酰肌醇（PtdIns）脂质PtdIns 3，5-P-2、PtdIns 5-P和PtdIns 4-P结合。与位于静息细胞的胞质溶胶中并易位至gp 91（phox）所在的质膜的p47（phox）不同，NOXO 1与Nox 1共定位于静息细胞的膜中。NOXO 1的这种定位是由其PX结构域决定的，因为该结构域而不是分子的其余部分定位于膜。全NOXO 1的PX结构域中的点突变降低了脂质结合，导致细胞溶质定位，并且还抑制了NOXO 1对Nox 1的激活。因此，在转染的HEK 293细胞中，NOXO 1和NOXA 1激活Nox 1而不需要激动剂激活，这部分是通过NOXO 1 PX结构域与膜脂质的结合介导的。
NOXO1 (Nox organizing protein 1) and NOXA1 (Nox activating protein 1) are homologs of p47(phox) and p67(phox). p47(phox) functions in phagocytes as an essential organizing protein mediating the binding of other regulatory proteins during activation of the phagocyte oxidase, and its translocation to the membrane is triggered upon cell activation by hyperphosphorylation, which relieves autoinhibition of SH3 and PX domains. NOXO1 lacks an autoinhibitory region and phosphorylation sites that are present in p47(phox). Co-transfection of Nox1, NOXO1, and NOXA1 reconstitutes ROS (reactive oxygen species) generation in HEK293 cells in the absence of cell stimulation. NOXO1 binds to the phosphatidylinositol (PtdIns) lipids PtdIns 3,5-P-2, PtdIns 5-P, and PtdIns 4-P. Unlike p47(phox), which is located in the cytosol of resting cells and translocates to the plasma membrane where gp91(phox) is located, NOXO1 co-localizes with Nox1 in the membranes of resting cells. This localization of NOXO1 is dictated by its PX domain, since this domain but not the remainder of the molecule localizes to membranes. A point mutation in the PX domain of holo-NOXO1 decreases lipid binding resulting in cytosolic localization and also inhibits NOXO1-activation of Nox1. Thus, in transfected HEK293 cells, NOXO1 and NOXA1 activate Nox1 without the need for agonist activation, and this is mediated in part by binding of the NOXO1 PX domain to membrane lipids.