Initial characterization of a factor from CHO wild type cells capable of activating the CHO tsH1 mutant leucyl-tRNA synthetase
Cirullo, Ronald E.
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The mechanism of action of mammalian aminoacy1-tRNA synthetases has been aided by the development of mutants in these enzymes particularly in the Chinese hamster ovary (CHO) cell line. Comparison of one of these mutants, tsHl, with the wild type parent strain has previously revealed ah altered leucyl-tRNA synthetase in the mutant. In this report, another difference between these two cell lines is described. A factor, originally discovered in crude wild type polysomal preparations, has been observed to stimulate the activity of the tsHl leucyl-tRNA synthetase to a level greater than that of its wild type counterpart. This factor is heat labile, and further characterization reveals that it is associated with the wild type leucyl-tRNA synthetase complex. This factor may represent another level of control of protein synthesis in mammalian cells.