Oka T, Tsuji H, Noda C, Sakai K, Hong Y M, Suzuki I, Muñoz S, Natori Y
Department of Nutrition, School of Medicine, University of Tokushima, Japan.
J Biol Chem. 1995 Dec 15;270(50):30060-7. doi: 10.1074/jbc.270.50.30060.
We found a novel protein in the postmitochondria supernatant fraction of rat liver, which is soluble in 5% perchloric acid and strongly inhibits protein synthesis in a rabbit reticulocyte lysate system. The protein extracted from the supernatant fraction with 5% perchloric acid was purified by ammonium sulfate fractionation and CM-Sephadex chromatography. The protein was shown to consist of two identical subunits with a molecular mass of 14 kDa. By immunoscreening with the rabbit antisera against the protein, a cDNA encoding the protein was cloned and sequenced. The cDNA contained an open reading frame of 411 base pairs encoding a 136-amino acid protein with a molecular mass of 14,149 Da. The deduced amino acid sequence was completely identical with that constructed from all of the above peptides. Interestingly, the perchloric acid-soluble protein inhibited cell-free protein synthesis in the rabbit reticulocyte lysate system in a different manner from RNase A. The protein is likely to inhibit an initiation stage of cell-free protein synthesis. Among the rat tissues tested, the protein was located only in liver and kidney. These findings are the first report on a new inhibitor that may be involved in the regulation of protein synthesis in those tissues.
我们在大鼠肝脏的线粒体后上清液组分中发现了一种新型蛋白质，它可溶于5%的高氯酸，并能强烈抑制兔网织红细胞裂解液系统中的蛋白质合成。用5%高氯酸从上清液组分中提取的蛋白质通过硫酸铵分级分离和CM-葡聚糖凝胶层析进行纯化。结果表明该蛋白质由两个分子量为14 kDa的相同亚基组成。通过用针对该蛋白质的兔抗血清进行免疫筛选，克隆并测序了编码该蛋白质的cDNA。该cDNA包含一个411个碱基对的开放阅读框，编码一个分子量为14,149 Da的136个氨基酸的蛋白质。推导的氨基酸序列与从上述所有肽段构建的序列完全相同。有趣的是，高氯酸可溶性蛋白以与核糖核酸酶A不同的方式抑制兔网织红细胞裂解液系统中的无细胞蛋白质合成。该蛋白质可能抑制无细胞蛋白质合成的起始阶段。在所测试的大鼠组织中，该蛋白质仅存在于肝脏和肾脏中。这些发现是关于一种可能参与这些组织中蛋白质合成调节的新抑制剂的首次报道。
