Blachly-Dyson E, Zambronicz E B, Yu W H, Adams V, McCabe E R, Adelman J, Colombini M, Forte M
Vollum Institute for Advanced Biomedical Research, Portland, Oregon.
J Biol Chem. 1993 Jan 25;268(3):1835-41.
The voltage-dependent anion channel (VDAC) of the outer mitochondrial membrane is a small abundant protein found in all eukaryotic kingdoms which forms a voltage-gated pore when incorporated into planar lipid bilayers. VDAC is also the site of binding of the metabolic enzymes hexokinase and glycerol kinase to the mitochondrion in what may be a significant metabolic regulatory interaction. Recently, there has been speculation that there may be multiple forms of VDAC in mammals which differ in their localization in the outer mitochondrial membrane and in their physiological function. In this report, we describe the identification and characterization of two human cDNAs encoding VDAC homologs (HVDAC1 and HVDAC2). To confirm VDAC function, each human protein has been expressed in yeast lacking the endogenous VDAC gene. Human proteins isolated from yeast mitochondria formed channels with the characteristics expected of VDAC when incorporated into planar lipid bilayers. In addition, expression of the human proteins in such strains can complement phenotypic defects associated with elimination of the endogenous yeast VDAC gene. Since VDAC is the site of binding of hexokinase to the outer mitochondrial membrane, the binding capacity of each VDAC isoform expressed in yeast mitochondria was assessed. When compared with the binding of hexokinase to mitochondria lacking VDAC, the results show that mitochondria expressing HVDAC1 are capable of specifically binding hexokinase, whereas mitochondria expressing HVDAC2 only bind hexokinase at background levels. The expression of each human cDNA has been assessed by Northern blot and polymerase chain reaction techniques. With one exception, each is expressed in all human cell lines and tissues examined.
线粒体外膜的电压依赖性阴离子通道（VDAC）是一种在所有真核生物界中都存在的丰富小蛋白，当整合到平面脂质双分子层中时会形成电压门控孔。VDAC也是代谢酶己糖激酶和甘油激酶与线粒体结合的位点，这可能是一种重要的代谢调节相互作用。最近，有人推测哺乳动物中可能存在多种形式的VDAC，它们在线粒体外膜中的定位及其生理功能有所不同。在本报告中，我们描述了两个编码VDAC同源物（HVDAC1和HVDAC2）的人类cDNA的鉴定和表征。为了证实VDAC的功能，每种人类蛋白都已在缺乏内源性VDAC基因的酵母中表达。从酵母线粒体中分离出的人类蛋白在整合到平面脂质双分子层中时形成了具有VDAC预期特征的通道。此外，在这些菌株中表达人类蛋白可以弥补与消除内源性酵母VDAC基因相关的表型缺陷。由于VDAC是己糖激酶与线粒体外膜结合的位点，因此评估了在酵母线粒体中表达的每种VDAC同工型的结合能力。与己糖激酶与缺乏VDAC的线粒体的结合相比，结果表明表达HVDAC1的线粒体能够特异性结合己糖激酶，而表达HVDAC2的线粒体仅在背景水平结合己糖激酶。每种人类cDNA的表达已通过Northern印迹和聚合酶链反应技术进行评估。除了一个例外，每种在所有检测的人类细胞系和组织中均有表达。
