Ono H, Tuboi S
Department of Biochemistry, Yamagata University School of Medicine, Japan.
Arch Biochem Biophys. 1990 Aug 1;280(2):299-304. doi: 10.1016/0003-9861(90)90333-t.
A cytosolic factor required for import of the precursor of mitochondrial protein into mitochondria was purified to homogeneity from a rabbit reticulocyte lysate by affinity column chromatography using a synthetic peptide containing the presequence of ornithine amino-transferase as a ligand. The molecular mass of the purified protein was estimated as 28 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The import of precursors of ornithine aminotransferase and sulfite oxidase into mitochondria was inhibited by anti-28-kDa protein IgG raised in guinea pigs. This antibody also blocked the binding of these precursors to mitochondria. These results suggest that the 28-kDa protein is an essential component of the import machinery in the cytosol and that anti-28-kDa protein IgG blocked the binding of the precursor of ornithine aminotransferase to mitochondria, but not the penetration step. Therefore, the 28-kDa protein may be a factor that should be named the "targeting factor" for import of mitochondrial protein.
通过使用含有鸟氨酸氨基转移酶前序列的合成肽作为配体的亲和柱色谱法，从兔网织红细胞裂解物中纯化出一种将线粒体蛋白前体导入线粒体所需的胞质因子，使其达到同质状态。通过十二烷基硫酸钠 - 聚丙烯酰胺凝胶电泳估计纯化蛋白的分子量为28 kDa。豚鼠中产生的抗28 kDa蛋白IgG可抑制鸟氨酸氨基转移酶和亚硫酸盐氧化酶前体导入线粒体。该抗体也阻断了这些前体与线粒体的结合。这些结果表明，28 kDa蛋白是胞质中导入机制的必需成分，抗28 kDa蛋白IgG阻断了鸟氨酸氨基转移酶前体与线粒体的结合，但未阻断穿透步骤。因此，28 kDa蛋白可能是一种应被命名为线粒体蛋白导入“靶向因子”的因子。
