Cahn F, Lubin M
J Biol Chem. 1978 Nov 10;253(21):7798-803.
We treated intact reticulocytes with nystatin to make them permeable to small cations and varied the concentration of K+ in the medium; the ionic strength was kept constant by adjusting Na+. As the intracellular K+ was lowered, the rate of protein synthesis decreased. In a reticulocyte lysate, the dependence of the rate of protein synthesis on K+ concentration (at constant ionic strength) was similar to that seen in nystatin-treated cells. We observed no loss of polysomes at low K+. Even when initiation was blocked with aurintricarboxylic acid, decreased K+ inhibited protein synthesis. Analysis of the kinetics of synthesis showed that lowering the K+ concentration inhibits the rate of elongation of nascent chains, but has little effect on the relative rate of initiation of chains.
我们用制霉菌素处理完整的网织红细胞，使其对小阳离子具有通透性，并改变培养基中K+的浓度；通过调节Na+使离子强度保持恒定。随着细胞内K+浓度降低，蛋白质合成速率下降。在网织红细胞裂解物中，蛋白质合成速率对K+浓度的依赖性（在恒定离子强度下）与在制霉菌素处理的细胞中观察到的相似。在低钾浓度下，我们未观察到多核糖体的丢失。即使在用金精三羧酸阻断起始过程时，降低K+浓度仍会抑制蛋白质合成。合成动力学分析表明，降低K+浓度会抑制新生链的延伸速率，但对链的起始相对速率影响不大。
