Thymidine transport in cultured mammalian cells. Kinetic analysis, temperature dependence and specificity of the transport system.
Thymidine transport in cultured mammalian cells. Kinetic analysis, temperature dependence and specificity of the transport system.
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胸苷在培养的哺乳动物细胞中的转运。
DOI：
10.1016/0005-2736(79)90231-1
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发表时间：
1979
期刊：
影响因子：
--
通讯作者：
P. Plagemann
中科院分区：
文献类型：
--
作者：
R. Wohlhueter;R. Marz;P. Plagemann
胸腺嘧啶的转运在培养的Novikoff大鼠肝癌细胞以及小鼠L细胞、中国仓鼠卵巢细胞、P388小鼠白血病细胞和HeLa细胞中进行了动力学和热力学表征。确保了与运输系统本身有关的特征，(i)采用最近开发的细胞/底物混合物快速取样方法，以便在细胞初次暴露于底物后几秒钟内跟踪同位素的运动；（ii）利用通过遗传或化学手段产生的不能代谢胸苷的细胞；并且（iii）通过证明输运数据与为简单的载波介导系统导出的综合速率方程的一致性。结果表明，胸腺嘧啶通过一个功能对称的非浓缩系统转运到哺乳动物细胞中，其载体-底物解离常数在中国仓鼠卵巢细胞中约为100 μM，在诺维科夫肝癌细胞中约为230 μM。在所有被研究的细胞系中，运输速度足以在15秒内几乎完全平衡低浓度的胸苷穿过膜。输运速度和底物：载流子解离的温度依赖性是连续的（ea = 18.3 kcal/mol， ΔH 0′= 9.3 kcal/mol），没有突变的迹象。几种天然的和人工的核苷和核酸抑制胸腺嘧啶的内流，显然是通过与胸腺嘧啶竞争运输载体。
The transport of thymidine has been characterized kinetically and thermodynamically in Novikoff rat hepatoma cells grown in culture and, less extensively, in mouse L cells, Chinese hamster ovary cells, P388 murine leukemia cells and HeLa cells. That the characterizations pertained to the transport system per se was ensured,(i) by employing recently developed methods for rapid sampling of cell/substrate mixtures in order to follow isotope movements within a few seconds after initial exposure of cells to substrate;(ii) by utilizing cells rendered, by genetic or chemical means, incapable of metabolizing thymidine; and,(iii) by demonstrating conformity of the transport data to an integrated rate equation derived for a simple, carrier-mediated system. The results indicate that thymidine is transported into mammalian cells by a functionally symmetrical, non-concentrative system for which the carrier: substrate dissociation constant ranges from about 100 μM in Chinese hamster ovary cells, to 230 μM in Novikoff hepatoma cells. In all cell lines investigated, the velocity of transport was sufficient to nearly completely equilibrate low concentrations of thymidine across the membrane within 15 s. Temperature dependence of transport velocity and substrate: carrier dissociation were continuous (E A= 18.3 kcal/mol, ΔH 0′= 9.3 kcal/mol, respectively), and showed no evidence of abrupt transitions. Several natural and artificial nucleosides and nucleic acid based inhibited influx of radiolabeled thymidine, apparently by competing with thymidine for the transport carrier.