The role of amino acids in the regulation of protein synthesis in perfused rat liver. I. Reduction in rates of synthesis resulting from amino acid deprivation and recovery during flow-through perfusion.
The role of amino acids in the regulation of protein synthesis in perfused rat liver. I. Reduction in rates of synthesis resulting from amino acid deprivation and recovery during flow-through perfusion.
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发表时间：
1982-03
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通讯作者：
K. Flaim;D. Peavy;W. Everson;L. Jefferson
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文献类型：
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作者：
K. Flaim;D. Peavy;W. Everson;L. Jefferson
使用灌流大鼠肝脏研究了灌流液氨基酸浓度在调节蛋白质合成速率中的作用。从喂养大鼠的肝脏灌注与nonrecycling介质和白蛋白和总蛋白的掺入[3 H]亮氨酸的条件下，亮氨酰-tRNALeu和灌注液亮氨酸的比活性是相等的和恒定的。在小于1小时的灌注过程中，总蛋白质的合成率是敏感的灌注液中的氨基酸的浓度。当不提供外源性氨基酸时，白蛋白和总蛋白的合成速率是当培养基中补充有5倍于正常血浆浓度的氨基酸时达到的最大速率的40%。然而，在肝脏灌注与氨基酸缺乏培养基的合成率上升，延长灌注的持续时间为95分钟。氨基酸缺乏引起的缺陷似乎没有导致减少收费的tRNA，因为没有变化的氨基酸结合到tRNA的数量发生在氨基酸缺乏灌注。蛋白质合成随时间的恢复被蛋白质水解抑制剂阻止，这表明蛋白质降解在这种现象中发挥了作用。
The role of perfusate amino acid concentrations in regulating rates of protein synthesis was investigated using the perfused rat liver. Livers from fed rats were perfused with a nonrecirculating medium and the incorporation of [3H]leucine into albumin and total protein was determined under conditions where the leucyl-tRNALeu and perfusate leucine specific activities were equal and constant. During perfusions of less than 1 h, rates of total protein synthesis were sensitive to the concentrations of amino acids in the perfusate. When no exogenous amino acids were provided, rates of synthesis of albumin and total protein were 40% of the maximal rates which were achieved when the medium was supplemented with 5 times the normal plasma concentrations of amino acids. However, rates of synthesis in livers perfused with amino acid-deficient medium rose with extension of the duration of perfusion to 95 min. The defect induced by amino acid deficiency did not appear to result from reductions in the charging of tRNA since no change in the quantities of amino acids bound to tRNA occurred in the amino acid-deficient perfusion. The recovery of protein synthesis with time was prevented by inhibitors of proteolysis suggesting a role for protein degradation in this phenomenon.