人类胸苷激酶1。规定在正常和恶性细胞。
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Munch-Petersen B, cloo L,詹森港元,Tyrsted G
人类胸苷激酶1。规定在正常和恶性细胞。
阿德酶Regul。1995; 35:69 - 89。0065 - 2571 . doi: 10.1016 / (94) 00014 - t。
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7572355 (在PubMed]
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在哺乳动物细胞中,救助途径胸苷磷酸化是由两个胸腺嘧啶核苷激酶催化:细胞循环调节细胞质TK1和既定的线粒体TK2表示。由于TK1非区分细胞几乎没有,TK2胸苷激酶可能是只存在于这些细胞。在细胞的新陈代谢,TK1和TK2大概会保持足够的dTTP DNA复制和修复。TK1纯化phytohemagglutinin-stimulated人类淋巴细胞是一个二聚体在没有和四聚物的存在ATP。除了分子量过渡,孵化与ATP在4摄氏度或存储与ATP产生可逆的,酶浓度,活动缓慢过渡从低到高亲和力的TK1形式,与14 microM microM和0.5公里值,分别。这种亲和力差异意味着在细胞胸苷浓度,催化活性的差异之间的两种TK1形式将3-5-fold。细胞TK1浓度的计算表明,低亲和力二聚体形式占主导地位在G0 / G1细胞和细胞的高亲和力四聚物形成s阶段。因此,转变为调整细胞循环调节胸苷激酶活动在翻译后水平上。在分子水平上研究ATP的效果,一个IPTG诱导T7 RNA polymerase-dependent表达系统为整个人类TK1多肽在大肠杆菌。重组TK1具有相同的单元质量和特定的活动作为原生酶。 However, the recombinant TK1 solely displayed the kinetics of the high affinity form, with Km values of 0.3-0.4 microM regardless of pre-exposure to ATP, indicating that the ATP effect may be dependent on post-translational modifications absent in E. coli. Surprisingly, we did not observe any effect of ATP on TK1 purified from bone-marrow cells from a patient with acute monocytic leukemia (AMOL). Furthermore, the Km values of TK1 from these cells were 45 microM for the ATP-free enzyme and 65 microM for the ATP-incubated enzyme. With TK1 purified from HL-60 cells, we obtained the same pattern and kinetic values as for TK1 from lymphocytes. In the light of the results with the recombinant TK1, we presume that the lack of ATP effect and very high Km values observed for the AMOL TK1 may be due to changes in post-translational regulatory mechanisms in acute monocytic cells.