| Research Abstract |
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.
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