Baker Mark A, Lane Darius J R, Ly Jennifer D, De Pinto Vito, Lawen Alfons
Department of Biochemistry and Molecular Biology, School of Biomedical Sciences, Monash University, Building 13D, 100 Wellington Road, Melbourne, Victoria 3800, Australia.
J Biol Chem. 2004 Feb 6;279(6):4811-9. doi: 10.1074/jbc.M311020200. Epub 2003 Oct 22.
Porin isoform 1 or VDAC (voltage-dependent anion-selective channel) 1 is the predominant protein in the outer mitochondrial membrane. We demonstrated previously that a plasma membrane NADH-ferricyanide reductase activity becomes up-regulated upon mitochondrial perturbation, and therefore suggested that it functions as a cellular redox sensor. VDAC1 is known to be expressed in the plasma membrane; however, its function there remained a mystery. Here we show that VDAC1, when expressed in the plasma membrane, functions as a NADH-ferricyanide reductase. VDAC1 preparations purified from both plasma membrane and mitochondria fractions exhibit NADH-ferricyanide reductase activity, which can be immunoprecipitated with poly- and monoclonal antibodies directed against VDAC(1). Transfecting cells with pl-VDAC1-GFP, which carries an N-terminal signal peptide, directs VDAC1 to the plasma membrane, as shown by confocal microscopy and FACS analysis, and significantly increases the plasma membrane NADH-ferricyanide reductase activity of the transfected cells. This novel enzymatic activity of the well known VDAC1 molecule may provide an explanation for its role in the plasma membrane. Our data suggest that a major function of VDAC1 in the plasma membrane is that of a NADH(-ferricyanide) reductase that may be involved in the maintenance of cellular redox homeostasis.
孔蛋白亚型1或电压依赖性阴离子选择性通道（VDAC）1是线粒体外膜中的主要蛋白质。我们之前证明，线粒体受到扰动时，质膜NADH-铁氰化物还原酶活性会上调，因此我们认为它作为一种细胞氧化还原传感器发挥作用。已知VDAC1在质膜中表达；然而，它在那里的功能仍是个谜。在此我们表明，VDAC1在质膜中表达时，作为NADH-铁氰化物还原酶发挥作用。从质膜和线粒体组分中纯化得到的VDAC1制剂均表现出NADH-铁氰化物还原酶活性，该活性可用针对VDAC1的多克隆和单克隆抗体进行免疫沉淀。用携带N端信号肽的pl-VDAC1-GFP转染细胞，共聚焦显微镜和流式细胞术分析表明，VDAC1定位于质膜，并显著增加转染细胞的质膜NADH-铁氰化物还原酶活性。知名的VDAC1分子的这种新酶活性可能解释了它在质膜中的作用。我们的数据表明，VDAC1在质膜中的主要功能是作为一种NADH（-铁氰化物）还原酶，可能参与维持细胞氧化还原稳态。
