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Katsuhiro Sakano, Regulation of Aspartokinase Isoenzyme Levels in Cultured Cells of Vinca rosea, Plant and Cell Physiology, Volume 22, Issue 7, November 1981, Pages 1343–1353, https://doi.org/10.1093/oxfordjournals.pcp.a076287
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Abstract
The levels of aspartokinase isoenzymes were followed as a function of days after transfer of V. rosea cells to fresh medium. When cells were subcultured in a 7-day cycle, both isoenzymes showed peaks at early, but not identical, stages of cell proliferation. Levels of the intracellular amino acids lysine, threonine, isoleucine and methionine decreased as the cellular level of protein increased. As soon as the increase in protein ceased, the amino acid level began to increase. The stationary cells accumulated large amounts of free amino acids. When late stationary cells were used as the inoculum, growth was slow and, as expected, it took longer before the depletion of endogenous free amino acids and the development of aspartokinase isoenzymes was significantly retarded. These results are further evidence that the syntheses of aspartokinase isoenzymes are under repression-derepression control in higher plants as they are in bacterial systems.
