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KMID : 0578319940040050099
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Molecules and Cells
1994 Volume.4 No. 5 p.99 ~ p.102
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Turnover of Glycerol Kinase during Starvation in Escherichia coli
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Kee, Yun
Jung, Eun Mi/Seol, Jae Hong/Lee, Chul Soon/Ha, Doo Bong/Chung, Chin Ha
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Abstract
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The level of glycerol kinase increased sharply during exponential growth when Escherichia coli K-12 cells were cultured in either Luria broth or Tris-minimal medium. However, after E. coli reached stationary phase, the enzyme level remained high in the cells grown in Luria broth but fell rapidly in the cells cultured in the minimal medium. Thus, the turnover rate of glycerol kinase appears to increase during stationary phase and such an increase may be due to exhaustion of certain essential nutrients in the minimal medium. When the cells were starved for nitrogen source or phosphate, the enzyme level decreased rapidly. In starvation of magnesium, the level also decreased but at a slower rate. In contrast, the enzyme level changed little when cells were starved for carbon source, although the average turnover rate of cell proteins is known to increase during starvation regardless of the type of nutrients starved. These results suggest that during starvation different signals activate proteolysis depending on the type of nutrients starved and therefore may provide not only selectivity of proteins to be hydrolyzed but also differential rates of proteolysis for different protein species.
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KEYWORD
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