Young R B, Schneible P A
Eur J Cell Biol. 1984 May;34(1):75-9.
Myosin heavy chain concentrations, synthesis rates and degradation rates were studied in muscle cell cultures prepared from the breast muscle of 13-day normal (white leghorn) and dystrophic (line 307) chicken embryos. Muscle cells were studied after 7 days in culture, at which time they had reached a steady state with respect to myofibrillar protein synthesis and degradation. The quantity of myosin heavy chain was 10.5 +/- 0.9 micrograms/culture (n = 32) in normal cells and 8.10 +/- 1.2 micrograms/culture (n = 31) in dystrophic cells. However, the myosin heavy chain synthesis rate was 23 500 molecules/min/nucleus in normal cells and 39 900 molecules/min/nucleus in dystrophic cells, as determined by pulse labeling with [3H]leucine and measurement of the specific radioactivity of tRNA precursor pools. Myosin heavy chain half-lives rates were calculated to be 30.6 h in normal cells and 15.6 h in dystrophic cells when corrections were made for reutilization of [3H]leucine. Thus, dystrophic muscle cultures accumulate less myosin heavy chain, despite their faster synthesis rate, because of faster degradation of myosin heavy chain.
在由13日龄正常（白来航鸡）和营养不良（307系）鸡胚胸肌制备的肌肉细胞培养物中，研究了肌球蛋白重链的浓度、合成速率和降解速率。在培养7天后对肌肉细胞进行研究，此时它们在肌原纤维蛋白合成和降解方面已达到稳定状态。正常细胞中肌球蛋白重链的量为10.5±0.9微克/培养物（n = 32），营养不良细胞中为8.10±1.2微克/培养物（n = 31）。然而，通过用[3H]亮氨酸脉冲标记并测量tRNA前体池的比放射性确定，正常细胞中肌球蛋白重链的合成速率为23500分子/分钟/细胞核，营养不良细胞中为39900分子/分钟/细胞核。当对[3H]亮氨酸的再利用进行校正时，正常细胞中肌球蛋白重链的半衰期计算为30.6小时，营养不良细胞中为15.6小时。因此，尽管营养不良的肌肉培养物合成速率较快，但由于肌球蛋白重链降解较快，其积累的肌球蛋白重链较少。
