Gilbert B E, Johnson T C
J Cell Biol. 1972 Apr;53(1):143-7. doi: 10.1083/jcb.53.1.143.
The measurement of protein turnover involves the product of the rates of protein synthesis and degradation. It is the dynamic balance between these two components that determines the measured net rate of protein synthesis. The data reported here show that brain cells from newborn animals incorporate arginine-(14)C into acid-insoluble protein at a rate 10-fold greater than the rate for brain cells obtained from 15-day old animals. This difference in incorporation occurred even though the rate of arginine accumulation and the resulting pool size of radioactive precursor were similar for both ages. The measurement of protein turnover in brain cell suspensions prepared from 1-day old animals was shown to be complex and to exhibit a cyclic phenomenon in regard to arginine-(14)C incorporation into and release from protein. The variation in half-life calculations (0.5-3.5 hr) due to this cyclic phenomenon is discussed. Although puromycin was added in an attempt to amplify the rate of degradation by preventing the synthesis of new protein, it was found that degradation was inhibited as well, suggesting a relationship between protein synthesis and degradation.
蛋白质周转的测量涉及蛋白质合成速率和降解速率的乘积。正是这两个组成部分之间的动态平衡决定了所测得的蛋白质合成净速率。此处报告的数据表明，新生动物的脑细胞将精氨酸 -（14）C掺入酸不溶性蛋白质的速率比从15日龄动物获得的脑细胞的速率高10倍。即使两个年龄段的精氨酸积累速率和放射性前体的最终池大小相似，掺入率仍存在这种差异。从1日龄动物制备的脑细胞悬液中蛋白质周转的测量显示很复杂，并且在精氨酸 -（14）C掺入蛋白质和从蛋白质中释放方面表现出循环现象。讨论了由于这种循环现象导致的半衰期计算的变化（0.5 - 3.5小时）。尽管添加了嘌呤霉素以试图通过阻止新蛋白质的合成来放大降解速率，但发现降解也受到抑制，这表明蛋白质合成与降解之间存在关系。
