Pines J, Hunter T
Molecular Biology and Virology Laboratory, Salk Institute for Biological Studies, San Diego, CA 92138.
New Biol. 1990 May;2(5):389-401.
In the yeast cell cycle, the induction of two very different processes, DNA synthesis (S-phase) and mitosis (M-phase), requires the same serine/threonine-specific protein kinase p34cdc2, which has been highly conserved through evolution. On the basis of work conducted largely in multicellular eukaryotes, it has recently been suggested that p34cdc2 is able to perform these two mutually exclusive roles by phosphorylating different sets of substrates through a cell cycle-dependent association with other proteins that dictate the substrate specificity of the protein kinase. To recognize its mitotic substrates, p34cdc2 associates with one of the cyclins--a family of proteins of two distinct but related types (A and B) characterized by their periodic destruction at each mitosis. In interphase, the formation of a complex between p34cdc2 and another protein (or proteins) would allow the phosphorylation of a different set of proteins involved in the G1 to S transition. This review focuses on the evidence for this appealing simple model and the nature of the putative substrates proposed.
在酵母细胞周期中，两种截然不同的过程，即DNA合成（S期）和有丝分裂（M期）的诱导，都需要同一种丝氨酸/苏氨酸特异性蛋白激酶p34cdc2，该激酶在进化过程中高度保守。基于主要在多细胞真核生物中开展的研究工作，最近有人提出，p34cdc2能够通过与其他决定蛋白激酶底物特异性的蛋白质进行细胞周期依赖性结合，磷酸化不同的底物集合，从而执行这两种相互排斥的功能。为了识别其有丝分裂底物，p34cdc2会与其中一种细胞周期蛋白结合——细胞周期蛋白是一类蛋白质，分为两种不同但相关的类型（A和B），其特点是在每次有丝分裂时都会周期性降解。在间期，p34cdc2与另一种蛋白质（或多种蛋白质）形成复合物，会使参与G1到S期转换的另一组蛋白质发生磷酸化。本文综述聚焦于这一引人注目的简单模型的证据以及所提出的假定底物的性质。
