IMR-32人神经母细胞瘤细胞中多种形式DNA聚合酶α的差异性抑制
Differential inhibition of multiple forms of DNA polymerase alpha from IMR-32 human neuroblastoma cells.
作者信息
Bhattacharya P, Simet I, Basu S
出版信息
Proc Natl Acad Sci U S A. 1981 May;78(5):2683-7. doi: 10.1073/pnas.78.5.2683.
Three forms of DNA polymerase (pol) alpha from human neuroblastoma IMR-32 were separated by DEAE column chromatography. All sedimented at approximately 7 S in 5-20% continuous sucrose density gradients. All were heat labile, with pol alpha 2 the most (90% inactivated) and pol alpha 3 the least (50% inactivated) sensitive to heating for 5 min at 50 degrees C. pol alpha 1 and alpha 2 efficiently utilized activated calf thymus DNA as template. The most active form, pol alpha 2, used both poly(dA).(dT)12-18 and poly(dT).(dA)12-18 as template at equal rates. Differential inhibition of DNA polymerase alpha activities was examined in the presence of ricin, hemin, and a nonhistone chromatin protein. All three polymerases were inhibited by both ricin (nonreduced) and hemin, with pol alpha 2 the most (80-90%) and pol alpha 3 the least (60%) sensitive in each case. In contrast, only pol alpha 2 and alpha 3 activities were inhibited (80-85%) by rat liver nonhistone chromatin protein.
通过DEAE柱色谱法分离出了来自人神经母细胞瘤IMR-32的三种形式的DNA聚合酶α（pol）。在5-20%连续蔗糖密度梯度中，所有形式均在约7S处沉降。所有形式对热均不稳定，其中polα2对50℃加热5分钟最为敏感（90%失活），而polα3最不敏感（50%失活）。polα1和α2能有效地将活化的小牛胸腺DNA用作模板。活性最高的形式polα2以相同速率将聚（dA）·（dT）12-18和聚（dT）·（dA）12-18均用作模板。在蓖麻毒素、血红素和一种非组蛋白染色质蛋白存在的情况下，检测了DNA聚合酶α活性的差异抑制情况。所有三种聚合酶均被蓖麻毒素（未还原）和血红素抑制，在每种情况下，polα2最为敏感（80-90%），polα3最不敏感（60%）。相比之下，大鼠肝脏非组蛋白染色质蛋白仅抑制polα2和α3的活性（80-85%）。
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