Staub M, Sasvari-Szekely M, Solymossy M, Szikla K
Institute of Biochemistry I, Semmelweis Medical University, Budapest, Hungary.
Adv Exp Med Biol. 1994;370:769-74. doi: 10.1007/978-1-4615-2584-4_161.
The salvage of nucleosides dominates over de novo biosynthesis in lymphocytes, polymorphonuclear cells (PMN) and in central neutral nervous system (CNS) in higher organisms. Earlier works in our laboratory have shown that the salvage of deoxycytidine (dCyd) did not correlate with DNA synthesis. The uptake and metabolism of dCyd was higher in undifferentiated germinal center lymphocytes and in follicles comparing to more differentiated cells. Recently we have compared the transport of thymidine (dThd), dCyd, uridine (Urd) and adenosine (Ado) in the three cell systems in which the salvage of nucleosides is dominating. It was found that dCyd was transported 30 times more effectively into lymphocytes than into PMN and synaptosomes, while Urd was transported about the same rate into the two cells and into synaptosomes. All transport processes could be inhibited by dipyridamole, NBRPR, papaverine and dilazep. The dCyd and dThd was phosphorylated even at 0 degrees C up to TTP and dCTP without incorporation into DNA and into liponucleotides. Our results show that the processes of transport-phosphorylation, as well as the processes of DNA-CDP-phospholipid synthesis are tightly coupled to each other in intact cells and organelles.
在高等生物的淋巴细胞、多形核细胞（PMN）和中枢神经系统（CNS）中，核苷的补救合成比从头生物合成占主导地位。我们实验室早期的研究表明，脱氧胞苷（dCyd）的补救合成与DNA合成无关。与分化程度更高的细胞相比，未分化的生发中心淋巴细胞和滤泡中dCyd的摄取和代谢更高。最近，我们比较了核苷补救合成占主导地位的三种细胞系统中胸苷（dThd）、dCyd、尿苷（Urd）和腺苷（Ado）的转运情况。结果发现，dCyd转运至淋巴细胞的效率比转运至PMN和突触体高30倍，而Urd转运至这两种细胞和突触体的速率大致相同。所有转运过程均可被双嘧达莫、NBRPR、罂粟碱和地拉齐普抑制。即使在0摄氏度时，dCyd和dThd也能磷酸化生成TTP和dCTP，而不会掺入DNA和脂核苷酸中。我们的结果表明，在完整细胞和细胞器中，转运磷酸化过程以及DNA - CDP - 磷脂合成过程彼此紧密耦合。
