一种糖缀合物可能参与IMR-32细胞的DNA合成：衣霉素处理后DNA聚合酶α2活性降低。
Probable involvement of a glycoconjugate in IMR-32 DNA synthesis: decrease of DNA polymerase alpha 2 activity after tunicamycin treatment.
作者信息
Bhattacharya P, Basu S
出版信息
Proc Natl Acad Sci U S A. 1982 Mar;79(5):1488-91. doi: 10.1073/pnas.79.5.1488.
Multiple forms of DNA polymerase alpha activity (alpha 1, alpha 2, and alpha 3) from human neuroblastoma IMR-32 cells untreated or treated with tunicamycin (3 microgram/ml) were separated by DEAE-cellulose column chromatography. Loss of 40--60% of DNA polymerase alpha 2 activity was observed in tunicamycin-treated cells. Ricin 1B, a subunit of intact ricin (Mr, 64,000), was found to be a specific inhibitor of DNA polymerase alpha 2 isolated from control IMR-32 cells. However, DNA polymerase alpha 2 isolated from tunicamycin-treated cells was insensitive to ricin 1B. Heat treatment studies at 50 degrees C showed two completely different inactivation profiles for the DNA polymerase alpha 2 enzymes isolated from the tunicamycin-treated and untreated cells. A probable involvement of a beta-linked galactose-containing carbohydrate chain in the catalytic subunit of DNA polymerase alpha 2 is suggested.
通过DEAE - 纤维素柱色谱法分离了来自未处理或用衣霉素（3微克/毫升）处理的人神经母细胞瘤IMR - 32细胞的多种形式的DNA聚合酶α活性（α1、α2和α3）。在用衣霉素处理的细胞中观察到DNA聚合酶α2活性丧失40 - 60%。蓖麻毒素1B是完整蓖麻毒素（Mr，64,000）的一个亚基，被发现是从对照IMR - 32细胞中分离出的DNA聚合酶α2的特异性抑制剂。然而，从用衣霉素处理的细胞中分离出的DNA聚合酶α2对蓖麻毒素1B不敏感。在50℃下的热处理研究显示，从用衣霉素处理和未处理的细胞中分离出的DNA聚合酶α2酶有两种完全不同的失活曲线。提示DNA聚合酶α2的催化亚基中可能存在与β相连的含半乳糖的碳水化合物链。
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