Hyver C, Le Guyader H
Département de Biologie, Centre d'Etudes Nucléaires de Saclay, Gif-sur-Yvette, France.
Biosystems. 1990;24(2):85-90. doi: 10.1016/0303-2647(90)90001-h.
The cell cycle appears to be controlled by the interplay between two protein complexes, MPF and cyclin. Their interactions play an essential role in the structure of the oscillator governing the cell cycle. There seems to be no general agreement on this latter crucial question. Two different mechanisms are proposed: (i) cyclin and p34 kinase combine to form an oligomer with MPF activity; (ii) cyclin enzymatically activates the passage from inactive pre-MPF to active MPF, with the postulate that MPF initiates cyclin degradation. We have modelled these two hypotheses to see whether both actually lead to oscillatory behaviour. The p34-cyclin oligomerization does so without any difficulty. With the second mechanism, however, the strict hypothesis that cyclin degradation is activated by MPF must be re-examined: the system only oscillates if, in disappearing, the MPF and the cyclin react with each other stoichiometrically. The model also demonstrates that it is useless to seek cyclic control of cyclin proteolysis.
细胞周期似乎是由两种蛋白质复合物，即MPF和细胞周期蛋白之间的相互作用所控制。它们的相互作用在调控细胞周期的振荡器结构中起着至关重要的作用。对于后一个关键问题，似乎尚未达成普遍共识。提出了两种不同的机制：（i）细胞周期蛋白和p34激酶结合形成具有MPF活性的寡聚体；（ii）细胞周期蛋白通过酶促作用激活从无活性的前MPF到有活性的MPF的转变，并假定MPF启动细胞周期蛋白的降解。我们对这两种假设进行了建模，以查看它们是否都能实际导致振荡行为。p34 - 细胞周期蛋白寡聚化能够毫无困难地做到这一点。然而，对于第二种机制，即细胞周期蛋白降解由MPF激活这一严格假设必须重新审视：只有当MPF和细胞周期蛋白在消失时以化学计量比相互反应，该系统才会振荡。该模型还表明，寻求细胞周期蛋白蛋白水解的循环控制是没有用的。
