Regulations of energy metabolism and cellular fate via mitochondrial porin

线粒体孔蛋白一直被认为是线粒体外膜上的一个“孔”。然而，最近的研究表明，线粒体！孔蛋白还调节细胞能量代谢和命运。在本研究中，我们对线粒体孔蛋白进行了表征，并获得了以下结果：1）在肿瘤细胞中，大量的己糖激酶附着在线粒体上。然而，当将可结合己糖的己糖激酶加入到肝线粒体中时，只有一小部分可以附着到线粒体。这一事实表明肝线粒体和肿瘤线粒体之间的己糖激酶结合位点（即孔蛋白）可能存在差异。在这项研究中，我们描述了恶性肿瘤细胞中表达的编码孔蛋白的信息。结果表明，肝细胞线粒体的己糖激酶结合能力低于肿瘤细胞线粒体的原因可以通过肝细胞和肿瘤细胞之间孔蛋白表达水平的差异来解释。2）通过基于简并引物的PCR鉴定了显示与1型孔蛋白结构相似的信息。这一结果表明可能存在线粒体孔蛋白的第四个成员。我们目前正在表征这种信息。3）孔蛋白的信息已经被很好地表征，但是存在于线粒体外膜中的孔蛋白蛋白还没有被研究。我们提出了针对孔蛋白的抗体和分析孔蛋白存在于线粒体馏分。结果，发现2型同种型是存在于线粒体外膜中的主要孔蛋白同种型。

Mitochondrial porin has been regarded just a "pore" in the outer mitbchohdrial membrane. However, recent studies indicated that mitochondria! porin also regulates cellular energy metabolism and fate. In this study, we characterized mitochondrial porin and obtained following results.1) In tumor cells, a large amount of hexokinase is attached to the mitochondria. However, when mitochondria-bindable hexokinase was added to liver mitochondria, only a small portion can be attached to the mitochondria. This fact indicates the possible differences in the hexokinase binding sites (i.e. porin) between liver mitochondria and tumor mitochondria. In, this study, we characterized messages encoding porin(s) expressed in malignant tumor cells. As a result, the reason why liver mitochondria show lower hexokinase binding capacity than tumor mitochondria was clearly explained by the differences in the expression levels of porin between liver and tumor cells.2) A message showing structural similarity to type 1 porin was identified by degenerated primer based PCR. This result indicates possible existence of fourth member of mitochondrial porin. We are currently characterizing this message.3) Messages of porin have been well characterized but porin protein present in the mitochondrial outer membrane has not yet investigated. We raised antibody against porin protein and analyzed porin protein present in the mitochondrial fraction. As a result, type 2 isoform was found to be major porin isoform present in the outer mitochondrial membrane.