Agris P F, Setzer D, Gehrke C W
Nucleic Acids Res. 1977 Nov;4(11):3803-19. doi: 10.1093/nar/4.11.3803.
S-adenosyl-L-methionine-tRNA methyltransferases of a murine leukemia cell line were found to exist in a high molecular weight enzyme complex. Aminoacyl-tRNA synthetase activity always co-chromatographed and co-sedimented with methyltransferase activity in evidence of a unique association of these two groups of enzymes. Molecular weight studies showed a probable molecular weight of 9 X 10(5) daltsons for the intact complex which dissociates to complexes of 6 X 10(5) and 3 X 10(5) daltons. The complexes contain discrete polypeptides of 25,000-90,000 daltons as determined from SDS-gel electrophoresis. High resolution fatty acid analysis showed that only very small amounts of saponifiable lipids were associated with the purified enzyme complex. Similarly very little protein-bound sugars was found within the complex indicating that neither lipids nor sugars were involved in the protein-protein interactions of the complex. Analysis of tRNA methylated in vitro indicated the presence of most methyltransferase activities in the purified complex. Of note was the absence from the complex of the methyltransferase responsible for the production of ribo Tp.
在一种小鼠白血病细胞系中发现,S-腺苷-L-甲硫氨酸-tRNA甲基转移酶以高分子量酶复合物的形式存在。氨酰-tRNA合成酶活性总是与甲基转移酶活性共色谱分离和共沉降,这证明了这两组酶之间存在独特的关联。分子量研究表明,完整复合物的可能分子量为9×10⁵道尔顿,它会解离为6×10⁵和3×10⁵道尔顿的复合物。根据SDS-凝胶电泳测定,这些复合物含有25,000 - 90,000道尔顿的离散多肽。高分辨率脂肪酸分析表明,纯化的酶复合物仅与极少量的可皂化脂质相关。同样,在复合物中发现的蛋白质结合糖也很少,这表明脂质和糖都不参与复合物的蛋白质-蛋白质相互作用。体外甲基化tRNA的分析表明,纯化的复合物中存在大多数甲基转移酶活性。值得注意的是,负责产生核糖Tp的甲基转移酶不存在于该复合物中。