"Molecular Characterization of the Additional Components of MPF Activity"

9405699 Kuang细胞生物学的核心问题之一是细胞周期中有丝分裂和减数分裂（M期）发生的调控机制。成熟促进因子（mature promoting factor， MPF）是一种M期特异性活性，其功能是诱导非洲爪蟾卵母细胞成熟（减数分裂），被认为是所有真核细胞的有丝分裂诱导因子。虽然目前MPF活性仅归因于p34cdc2激酶/细胞周期蛋白B复合物，但该提议为工作假设提供了证据，即MPF活性是由于一个由p34cdc2/细胞周期蛋白B、抗磷酸化表位抗体MPM-2识别的至少三种不同蛋白质和磷酸化这些MPM-2抗原的激酶组成的自催化系统。具有强积金活性的三种MPM-2抗原包括已鉴定的cdc2激酶激活剂cdc25和两种未鉴定的cdc2激酶激活剂MPF- qe1和MPF- qe2。磷酸化这三种MPM-2抗原的激酶依次被p34cdc2/cyclin b激活。为了验证这一假设，本研究旨在纯化和分子克隆MPF- qe1、MPF- QE2以及磷酸化MPM-2表位的激酶。cDNA克隆的可用性将促进纯化蛋白和抗体的产生。这些试剂将允许表征它们各自在cdc2激酶激活和m期诱导中的贡献。从MPF活性的附加成分的分子特征中产生的信息可能会极大地促进我们对真核细胞周期中m期诱导的调控的理解。这个建议涉及到细胞周期过程的研究，所有细胞都是通过这个过程增殖的。在正常条件下，细胞增殖产生大量的细胞，这些细胞组成了生物体，并允许它们生长和再生。相反，不受控制的细胞增殖往往导致疾病，如癌症。因此，细胞周期的控制是生物学中最基本的问题之一。这一建议解决了细胞周期的控制，调控有丝分裂起始的分子机制。该提案的驱动假设是MPF是一个多组分系统，在有丝分裂的启动中起着“决策委员会”的作用。该提案的最终目标是确定该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. ***