"Molecular Characterization of the Additional Components of MPF Activity"

9405699细胞生物学的核心问题之一是调控细胞周期中有丝分裂和减数分裂(M期)的启动的控制机制。成熟促进因子(MPF)是一种M期特异性活性物质，其功能取决于其诱导非洲爪哇卵母细胞成熟(减数分裂)的能力，被认为是所有真核细胞的有丝分裂诱导剂。虽然目前MPF的活性完全归因于p34cdc2激酶/细胞周期蛋白B复合体，但这一建议为以下假设提供了证据：MPF活性是由p34cdc2/细胞周期蛋白B、至少三个被抗磷表位抗体MPM-2识别的不同蛋白质和使这些MPM-2抗原磷酸化的激酶(S)组成的自催化系统。这三个具有MPF活性的MPM-2抗原包括已知的CDC2激酶激活剂CDC25和两个未知的CDC2激活剂，分别命名为MPF-QE1和MPF-QE2。磷酸化这三种MPM-2抗原的激酶(S)又被p34cdc2/Cyclin B激活。为了验证这一假说，本研究旨在对MPF-QE1、MPF-QE2及其上的磷酸化MPM-2表位的激酶进行纯化和分子克隆。它们的cDNA克隆的可获得性将促进纯化的蛋白和抗体的产生。这些试剂将能够表征它们在激活cdc2激酶和M期诱导中各自的作用。从MPF活性附加成分的分子表征中获得的信息很可能会大大有助于我们理解真核细胞周期中M期诱导的调控。%这项建议涉及对称为细胞周期的过程的研究，所有细胞都通过这个过程进行增殖。在正常情况下，细胞增殖会产生大量活的有机体组成的细胞，并允许它们的生长和再生。相反，不受控制的细胞增殖往往会导致癌症等疾病。因此，细胞周期的控制是生物学中最基本的问题之一。这项建议涉及细胞周期的控制，这是调节有丝分裂启动的分子机制。该提案的驱动假设是，强积金是一个多组分的系统，扮演着启动有丝分裂的“决策委员会”的角色。该提案的最终目标是确定这一过程的所有重要组成部分，并确定它们在细胞周期过程中的相互作用。***

9405699 Kuang One of the central problems in cell biology is the control mechanism regulating the initiation of mitosis and meiosis (M phase) during the cell cycle. Maturation promoting factor (MPF), which is an M phase-specific activity functionally defined by its ability to induce Xenopus oocyte maturation (meiotic division), is hypothesized to be the mitotic inducer in all eukaryotic cells. Although currently MPF activity is attributed solely to the p34cdc2 kinase/cyclin B complex, this proposal has provided evidence for the working hypothesis that MPF activity is due to an autocatalytic system consisting of p34cdc2/cyclin B, and at least three distinct proteins recognized by the anti-phosphoepitope antibody MPM-2, and the kinase(s) that phosphorylate these MPM-2 antigens. The three MPM-2 antigens with MPF activity include the identified activator of cdc2 kinase, cdc25, and two unidentified activators of cdc2 kinase, designated MPF-QE1 and MPF-QE2. The kinase(s) that phosphorylate these three MPM-2 antigens are in turn activated by p34cdc2/cyclin B. To examine this hypothesis, the proposed research is aimed at the purification and molecular cloning of MPF-QE1, MPF- QE2 and the kinase that phosphorylates the MPM-2 epitope on them. Availability of their cDNA clone will facilitate the generation of the purified proteins and antibodies against them. These reagents will allow the characterization of their respective contribution in the activation of cdc2 kinase and M-phase induction. It is likely that information generated from the molecular characterization of the additional components of MPF activity will significantly facilitate our understanding of the regulation of M-phase induction during the eukaryotic cell cycle. %%% This proposal concerns the study of the process called cell cycle, by which all cells proliferate. Cell proliferation under normal conditions gives rise to the multitude of cells that living organisms are composed of and allows for their growth and regeneration. Conversely, uncontrolled cell proliferation often results in disorders such as cancer. Thus the control of cell cycle is one of the most fundamental problems in biology. This proposal addresses the control of cell cycle, the molecular mechanism that regulates the initiation of mitosis. The driving hypothesis of the proposal is that MPF is a multicomponent system that plays the role of the "decision committee" for the initiation of mitosis. The ultimate goal of the proposal is to identify all important components of this process and to determine their interaction in the cell cycle process. ***