Cladaras C, Cottam G L
J Biol Chem. 1980 Dec 10;255(23):11499-503.
Poly(A+) RNA (RNA containing a polyadenylic acid sequence) was isolated from individual livers of rats fed standard lab chow, fasted, or fasted and refed a high carbohydrate diet. The level of functional mRNA coding for pyruvate kinase was assayed using a rabbit reticulocyte in vitro translation system. The total 35S incorporation into newly synthesized liver pyruvate kinase was measured and compared to 35S incorporation into albumin, total trichloroacetic acid-precipitated proteins, and released polypeptide chains. The relative level of mRNA coding for liver pyruvate kinase decreases almost 60% upon fasting and increases approximately 15-fold upon refeeding with a high carbohydrate diet for 24 h. These observed changes in the amount of mRNA coding for liver pyruvate kinase agree with the previously reported changes in the relative rates of liver pyruvate kinase synthesis measured in vivo during these dietary stresses. Thus, it is suggested that the alterations in the amount of pyruvate kinase in liver in response to these dietary stresses primarily result from alteration in the amount of functional mRNA coding for the enzyme.
从喂食标准实验室饲料、禁食或禁食后再喂食高碳水化合物饮食的大鼠的个体肝脏中分离出聚腺苷酸加尾RNA（Poly(A+) RNA，即含有聚腺苷酸序列的RNA）。使用兔网织红细胞体外翻译系统测定编码丙酮酸激酶的功能性mRNA的水平。测量了新合成的肝脏丙酮酸激酶中35S的总掺入量，并与白蛋白、三氯乙酸沉淀的总蛋白和释放的多肽链中的35S掺入量进行了比较。禁食时，肝脏丙酮酸激酶编码的mRNA相对水平几乎降低60%，而在喂食高碳水化合物饮食24小时后再喂食时，该水平会增加约15倍。观察到的肝脏丙酮酸激酶编码的mRNA量的这些变化与先前报道的在这些饮食应激期间体内测量的肝脏丙酮酸激酶合成相对速率的变化一致。因此，有人认为，肝脏中丙酮酸激酶量的变化响应这些饮食应激，主要是由于编码该酶的功能性mRNA量的改变所致。
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