Prolyl-tRNA-based rates of protein and collagen synthesis in human lung fibroblasts.
Prolyl-tRNA-based rates of protein and collagen synthesis in human lung fibroblasts.
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人肺成纤维细胞中基于脯氨酰-tRNA 的蛋白质和胶原蛋白合成率。
DOI：
10.1042/bj1980249
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发表时间：
1981
期刊：
影响因子：
--
通讯作者：
Low,RB
中科院分区：
文献类型：
--
作者：
Hildebran,JN;Airhart,J;Stirewalt,WS;Low,RB
了解胶原蛋白更新的动态需要有关这组结缔组织蛋白的合成速率的信息。已知各种氨基酸库与用于蛋白质合成的 tRNA 前体库的关系在不同细胞类型和组织之间存在差异，甚至对于必需氨基酸也是如此。我们研究了培养的人肺 IMR-90 成纤维细胞中的细胞外、细胞内和 tRNA-脯氨酸库，以确定它们作为总蛋白和胶原合成的候选脯氨酸前体库之间的关系。时程实验表明，在细胞外脯氨酸浓度为 0.2 mM 时，三个脯氨酸池获得了明显不同的稳态特异性放射性（细胞外大于细胞内大于 tRNA）。放射性同位素掺入细胞蛋白和胶原酶可消化蛋白的动力学表明，细胞内游离脯氨酸库不能可靠地用作计算合成率的前体。然而，tRNA-脯氨酸的同位素行为就好像它是前体一样，并且提供的合成率比使用任一游离脯氨酸池计算的合成率高 2-3 倍。标记的赖氨酸和亮氨酸的掺入在很宽的细胞外脯氨酸浓度范围内是恒定的。 [3H]苯丙氨酸基于tRNA-氨基酸的蛋白质合成分数率与[3H]脯氨酸相同。施用放射性同位素后 8-10 小时，细胞相关羟脯氨酸的比放射性达到稳态值，与平均 tRNA-脯氨酸比放射性相匹配，表明 tRNA-脯氨酸不是同位素区室化的。提出并讨论了细胞脯氨酸池关系的模型。
Knowledge of the dynamics of collagen turnover requires information regarding rates of synthesis of this group of connective-tissue proteins. The relationship of various amino acid pools to the tRNA precursor pool used for protein synthesis is known to vary between different cell types and tissues, even for essential amino acids. We studied extracellular, intracellular and tRNA-proline pools in cultured human lung IMR-90 fibroblasts to determine the relationship between them as candidate proline precursor pools for total protein and collagen synthesis. Time-course experiments showed that the three proline pools attained distinctly different steady-state specific radioactivities (extracellular greater than intracellular greater than tRNA) at the extracellular proline concentration of 0.2 mM. The kinetics of radioisotope incorporation into cell protein and collagenase-digestible protein indicated that the intracellular free proline pool could not be used reliably as a precursor for calculating synthetic rates. However, tRNA-proline behaved isotopically as if it were the precursor and provided synthesis rates 2-3-fold higher than those calculated by using either free proline pool. The incorporation of labelled lysine and leucine was constant over a wide range of extracellular proline concentrations. Fractional rates of protein synthesis based on tRNA-amino acid were the same with [3H]phenylalanine as with [3H]proline. The specific radioactivity of cell-associated hydroxyproline reached a steady-state value 8-10h after radioisotope administration which matched the mean tRNA-proline specific radioactivity, suggesting that tRNA-proline is not isotopically compartmentalized. A model of cellular proline-pool relationship is presented and discussed.