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Mechanism of targeting and transport of mitochondrial precursor proteins to mitochondria

线粒体前体蛋白靶向和转运至线粒体的机制

基本信息

批准号：
04670135
负责人：
ISHIKAWA Kazunobu
金额：
$ 1.34万
依托单位：
Yamagata University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1993
项目状态：
已结题

项目摘要

Although no binding of porin-precursor to trypsin-pretreated rat liver mitochondria was detectable, its integration into these mitochondria was observed to some extent, possibly by the bypass-import system first demonstrated in fungus mitochondria. A topographical study of this bypass-import system demonstrated that import of porin occurs at contact sites between the outer and inner membrane. Furthermore, antibodies to 29 KDa outer membrane protein, a component of the import machinery in contact sites for precursors of ornithine aminotransferase and sulfite oxidase, inhibited the integration of porin, suggesting that the 29 KDa protein is involved in the imports of most mitochondrial precursor proteins.When inverted vesicles prepared from the inner membrane of rat liver mitochondria were incubated with prepro-rat serum albumin, considerable amounts of prepro-albumin and pro-albumin were recovered with the inverted vesicles re-isolated by centrifugation. Pro-albumin was resistant to trypsin, but prepro-albumin was completely digested by trypsin, indicating that prepro-albumin was transported into the vesicles and concomitantly converted to pro-albumin. This transport process required ATP, but not a membrane potential. These results suggest that some export machinery for a protein having an amino acid sequence in its N-terminal portion similar to the signal sequence of secretory protein exists in the inner mitochondrial membrane.

虽然没有结合的孔蛋白前体胰蛋白酶预处理的大鼠肝线粒体是可检测的，其整合到这些线粒体中观察到一定程度上，可能是由旁路进口系统首次证明在真菌线粒体。这旁路进口系统的地形研究表明，进口的孔蛋白发生在外膜和内膜之间的接触部位。此外，29 KDa外膜蛋白（鸟氨酸氨基转移酶和亚硫酸盐氧化酶前体接触位点的输入机制的组成部分）的抗体抑制孔蛋白的整合，表明29 KDa蛋白参与大多数线粒体前体蛋白的输入。回收了相当大量的前白蛋白原和白蛋白原，并通过离心重新分离倒置的囊泡。前白蛋白对胰蛋白酶有抗性，但前白蛋白原被胰蛋白酶完全消化，表明前白蛋白原被转运到囊泡中并伴随转化为前白蛋白。这个转运过程需要ATP，而不是膜电位。这些结果表明，一些出口机械的蛋白质具有类似的信号序列的分泌蛋白的N-末端部分的氨基酸序列存在于线粒体内膜。