Stoichiometry and composition of an aminoacyl-tRNA synthetase complex from rat liver.
Stoichiometry and composition of an aminoacyl-tRNA synthetase complex from rat liver.
复制标题
大鼠肝脏氨酰-tRNA 合成酶复合物的化学计量和组成。
DOI：
10.1073/pnas.78.7.4059
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发表时间：
1981
影响因子：
11.1
通讯作者：
Yang,DC
中科院分区：
文献类型：
--
作者：
Johnson,DL;Yang,DC
大鼠肝颗粒氨酰-tRNA合成酶共纯化约1000倍，单个合成酶活性的产率超过20%。氨酰化活性的测定表明，在纯化的复合物中，赖氨酰-、氨酰-、亮氨酰-、异亮氨酰-和甲硫氨酰-tRNA合成酶在18 S处共沉淀。合成酶复合物的分子量约为一百万，如通过凝胶过滤估计的。合成酶在复合物中的化学计量用氨酰腺苷酸活性位点滴定法测定。结果表明，18 S合成酶复合物含有一个甲硫氨酰-tRNA合成酶亚基和两个赖氨酰-tRNA合成酶亚基。十二烷基硫酸钠存在下的聚丙烯酰胺凝胶电泳表明，18 S合成酶复合物包含8个主要蛋白带。亚基分子量为104，000、92，000、69，000和67，000的蛋白质以1：1：2：2的摩尔比存在，而亚基分子量为104，000、92，000、69，000和67，000的蛋白质以1：1：2：2的摩尔比存在。这些结果表明，颗粒氨酰-tRNA合成酶存在作为一个异型多酶复合物具有明确的结构。
The particulate aminoacyl-tRNA synthetases of rat liver were copurified about 1000-fold with more than 20% yields for individual synthetase activities. Measurements of aminoacylation activities showed that lysyl-, arginyl-, leucyl-, isoleucyl-, and methionyl-tRNA synthetases in the purified complex cosedimented at 18 S. The molecular weight of the synthetase complex is about one million, as estimated by gel filtration. The stoichiometry of the synthetase in the complex was determined by active site titration with aminoacyl adenylates. Results indicate that the 18S synthetase complex contains one subunit of methionyl-tRNA synthetase and two subunits of lysyl-tRNA synthetase. Polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate showed that the 18S synthetase complex contains eight major protein bands. Proteins with subunit molecular weights of 104,000, 92,000, 69,000, and 67,000 are present in molar ratios of 1:1:2:2, while proteins with subunit molecular weights of amounts. These results suggest that the particulate aminoacyl-tRNA synthetases exist as a heterotypic multienzyme complex with defined structure.