Engström Y, Eriksson S, Jildevik I, Skog S, Thelander L, Tribukait B
J Biol Chem. 1985 Aug 5;260(16):9114-6.
Consistent with its specialized role in DNA synthesis, the activity of ribonucleotide reductase is cell cycle-dependent, reaching its maximum during S-phase. This paper demonstrates, however, the levels of the two protein subunits, M1 and M2, of this enzyme vary independently of one another. The level of protein M1 was determined by use of a two-site monoclonal antibody-enzyme immunoassay and found to be constant throughout the cell cycle in bovine kidney MDBK cells. Pulse-chase experiments showed that the half-life of protein M1 was 15 h. This contrasts with our previous results demonstrating an S-phase-correlated increase in the concentration of protein M2 and a half-life of this subunit of 3 h. Therefore, ribonucleotide reductase is controlled during the cell cycle by the level of protein M2.
与它在DNA合成中的特殊作用相一致，核糖核苷酸还原酶的活性是细胞周期依赖性的，在S期达到最大值。然而，本文证明，该酶的两个蛋白质亚基M1和M2的水平彼此独立变化。通过使用双位点单克隆抗体-酶免疫测定法测定蛋白质M1的水平，发现其在牛肾MDBK细胞的整个细胞周期中保持恒定。脉冲追踪实验表明蛋白质M1的半衰期为15小时。这与我们之前的结果形成对比，之前的结果表明蛋白质M2的浓度在S期相关增加，且该亚基的半衰期为3小时。因此，核糖核苷酸还原酶在细胞周期中受蛋白质M2水平的控制。
