Litt M, Howell-Litt R
J Biol Chem. 1980 Jan 25;255(2):375-8.
In eukaryotes, the concentrations of specific tRNAs are closely correlated with the demands for their cognate amino acids in protein synthesis. To account for this phenomenon, we have proposed that the extent of aminoacylation of a given tRNA species in vivo controls the relative rate of synthesis or degradation of that species. Previously, we reported the Friend leukemia cells respond to deprivation of histidine, leucine, or tryptophan by specifically increasing the relative concentration of tRNAs cognate to the deprived amino acid (Weiser, K., and Litt, M. (1979) Eur. J. Biochem. 93, 295-300). In this paper, we show that this is also true for phenylalanine and we report studies of the relative rates of synthesis and degradation of tRNAPhe in phenylalanine-deprived and control cells. We find that deprivation of phenylalanine has no effect on the relative rate of synthesis of tRNAPhe, but does induce a decline in the relative rate of degradation of tRNAPhe which accounts quantitatively for the increase in its relative steady state concentration as measured by in vitro aminoacylation. We conclude that, in Friend leukemia cells, deacylated tRNA species are more stable than charged tRNA species.
在真核生物中，特定tRNA的浓度与蛋白质合成中其同源氨基酸的需求密切相关。为了解释这一现象，我们提出，体内给定tRNA种类的氨酰化程度控制着该种类合成或降解的相对速率。此前，我们报道了弗瑞德白血病细胞通过特异性增加与被剥夺氨基酸同源的tRNA的相对浓度来应对组氨酸、亮氨酸或色氨酸的缺乏（韦泽尔，K.，和利特，M.（1979年）《欧洲生物化学杂志》93卷，295 - 300页）。在本文中，我们表明苯丙氨酸的情况也是如此，并且我们报道了在苯丙氨酸缺乏的细胞和对照细胞中tRNAphe合成和降解的相对速率的研究。我们发现，苯丙氨酸的缺乏对tRNAphe的相对合成速率没有影响，但确实会导致tRNAphe的相对降解速率下降，这在数量上解释了通过体外氨酰化测量的其相对稳态浓度的增加。我们得出结论，在弗瑞德白血病细胞中，去酰化的tRNA种类比带电的tRNA种类更稳定。
