title: A complex from cultured Chinese hamster ovary cells containing nine aminoacyl-tRNA synthetases. Thermolabile leucyl-tRNA synthetase from the tsH1 mutant cell line is an integral component of this complex.
abstract: The size distribution of the 20 aminoacyl-tRNA synthetases from wild-type Chinese hamster ovary (CHO) cells and from the mutant cell line tsH1, containing a temperature-sensitive leucyl-tRNA synthetase, was determined by gel filtration. Nine aminoacyl-tRNA synthetases, specific for arginine, aspartic acid, glutamic acid, glutamine, isoleucine, leucine, lysine, methionine and proline, which coeluted as high-Mr entities (Mr approximately 1.2 X 10(6)), were further co-purified to yield a multienzyme complex, the polypeptide composition of which was identical to that previously determined for the complex from rabbit liver. Immunoprecipitates obtained from crude extracts of wild-type and tsH1 mutant cells, using specific antibodies directed to the lysyl-tRNA or methionyl-tRNA synthetase components of the complex, displayed the same polypeptide compositions as that of the purified complex, thereby establishing the heterotypic nature of this complex. Although the activity of leucyl-tRNA synthetase from the mutant cells, grown at a permissive temperature, was low compared to that from the wild-type, the polypeptide of Mr 129 000, corresponding to this enzyme, was present in similar amounts and occurred exclusively as a component of the high-Mr complex. Finally, we report that attempts to demonstrate phosphorylation of the components of the complex from cultured CHO, HeLa and C3 cells were unsuccessful.
mesh_terms: D000604:Amino Acyl-tRNA Synthetases / Q000302:isolation & purification*; D000818:Animals; D002460:Cell Line; D011232:Chemical Precipitation; D002850:Chromatography, Gel; D006224:Cricetinae; D003412:Cricetulus; D005260:Female; D006367:HeLa Cells; D006801:Humans; D007120:Immunochemistry; D007668:Kidney; D007935:Leucine-tRNA Ligase / Q000302:isolation & purification*; D008099:Liver; D007614:Macropodidae; D008970:Molecular Weight; D009097:Multienzyme Complexes / Q000302:isolation & purification*; D009154:Mutation; D010053:Ovary; D010766:Phosphorylation; D051381:Rats; D013696:Temperature
chemical_list: D009097:Multienzyme Complexes; D000604:Amino Acyl-tRNA Synthetases; D007935:Leucine-tRNA Ligase