Studies on the mechanism of cell division in animal cells.

[CALL增殖的信号转导机制]：我们证实了在生长因子或佛波酯(癌变促进剂)刺激培养的哺乳动物细胞后，高分子量微管相关蛋白(MAP)的磷酸化以及MAP-2蛋白的激活，并进一步鉴定了一种不能磷酸化组蛋白或酪蛋白而仅能磷酸化MAP-2和髓鞘碱性蛋白的蛋白激酶，被证明是一种新发现的蛋白激酶。我们进一步证明，由微管破坏药物产生的微管的分解直接发出细胞增殖的信号，而不需要生长因子或法波酯的刺激。这些结果有力地表明MAP-2激酶参与了细胞增殖的信号转导中的磷酸化级联反应，并证明了微管细胞骨架与信号转导直接相关，从而在机制上提出了一个新的概念。[有丝分裂装置形成的机制]…此外：我们鉴定了中心体的主要蛋白质组分，51-kD蛋白质，并证明了在存在对偶体和微管蛋白的一些次要成分的情况下，它具有抗原性。该蛋白的碱性蛋白等电点为9.8，具有结合鸟嘌呤核苷酸、GTP和GDP的能力，并被证明是一种G蛋白。此外，我们还证明了GTP和GDP之间的相互转换结合在51-kD的蛋白上，GTP形式的蛋白可以作为微管组装的信号蛋白。这为有丝分裂器官的形成机制提供了一个新的观点，即51-kD蛋白位点上的GTP&lt；双箭头&gt；GDP相互转换控制着对生体启动微管建立雄蕊和纺锤体的能力。事实上，我们证明了被GTP饱和的分离的中心体片段(与被GTP饱和的51-kD蛋白)可以比那些被GDP饱和的片段更有效地启动星形微管。[切割信号的转导机制]：我们纯化了与切割信号作为易位马达最有可能的转导有关的Kinesin，并对其酶性质进行了表征。我们进一步分离和纯化了一个260-kD的蛋白，它位于细胞膜下，正好与收缩环中的肌动蛋白束共定位。体外实验表明，260-kD的蛋白质可形成卷曲的粗大肌动蛋白束。此外，一个重要的发现是，标记了WGA的跨膜糖蛋白通过切割信号的作用，沿着预测的收缩环组装成前体结构，该切割信号被证明依赖于微管，可能是星形微管。较少

[Mechanism of signal transduction for call proliferatrion] : We demonstrated phosphorylation of high molecular weight microtubule-associated proteins (MAPS) as well as activation of a MAP-2 kinase after stimulation of cultured mammalian cells by growth factor or phorbol ester (promoter of carcinogenesis) and further identified a protein kinase which does not phosphorylate histone or casein but only MAP-2 and myelin basic-protein, proved to be a protein kinase newly identified. We further demonstrated that disassembly of microtubules produced by microtubule-disrupting drugs directly signals cell proliferation without stimulation by growth factor or pharbol ester. These results strongly suggest that MAP-2 kinase is involved in the cascade of phosphorylation in signal transduction for cell proliferation and demonstrate that microtubule cytoskeleton is directly relevant to the signal transduction, raising a now concept in the mechanism.[Mechanism of the formation of the mitotic apparatus] … More : We identified the major protein component of the centrasons, 51-kD protein, and demonstrated its aster forming ability in the presence of some minor components of the contrasome and tubulin. The protein, which has an isoelectric point of 9.8 as basic protein, has an ability to bind guanine nucleotide, GTP and GDP, and proved to be a G protein. Furthermore, we demonstrated interconversion between GTP and GDP bound to the 51-kD protein, and the GTP-form protein is competent to be a signal protein for microtubule assembly. This provided a new standpoint in the mechanism of the formation of the mitotic apparatus, that is, the GTP<double arrow>GDP interconversion in the 51-kD protein sites governs the ability of the contrasome to initiate microtubules to build up the aster and the spindle. In fact, we demonstrated that isolated centrosomal fragments saturated with GTP (with the 51-kD protein saturated with GTP) can initiate astral microtubules much more efficiently than those saturated with GDP.[Mechanism of transduction of cleavage signal] : We purified kinesin, which is most likely concerned with the trainduction of cleavage signal as a translocation motor, and characterized its enzymatic properties. We further isolated and purified a 260-kD protein which localizes underneath the cell membrane Just co-localized with actin bundles in the contractile ring. The 260-kD protein was shown to form curled thick actin bundles in vitro. Furthermore, an important finding is that a transmembrane glycoprotein labeled with WGA assembles as a precursor structure along the predicted contractile ring through the action of the cleavage signal which was shown to be dependent on microtubules, possibly astral microtubules. Less