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. ***
