The Role of NDP kinases in Membrane Signal Transduction

I.信号转导和NDP激酶NDP激酶可能参与这些信号转导系统的提出，最初是基于观察到激素可以在GTP存在的情况下激活大鼠肝脏和人血小板膜上的效应器腺酰环化酶。NDP激酶似乎是这些信号转导系统中G蛋白的受体激活介导的GTP供应机制。Orlov博士在TMIG中进一步研究了NDP激酶和信号转导系统的关系。与其他组织相比，牛视网膜杆外段(ROS)的信号转导成分极其集中。ROS中的可溶性NDP激酶发现制剂在pH值下与ROS膜相互作用，一价和二价阳离子依赖的方式。在酸性pH和低离子强度下，通过GTP或其类似物(GTP GammaS，GppNHp)释放与膜结合的NDP激酶。结果表明，转导蛋白(GT)似乎参与了可溶性NDP激酶与漂白的ROS膜的高亲和力和GTP敏感的相互作用。II.参加国际研讨会并访问NIHDr木村和石川参加了在巴黎巴斯德研究所举行的第一次国际研讨会，并作了题为《NDP激酶/nm23在细胞功能中的作用》和《大鼠NDP激酶形式基因：结构和表达》的报告，值得注意的是，木村博士主持了一次会议。然后，他们访问了美国国立卫生研究院的Liotta博士，就NDP激酶/nm23作为候选肿瘤转移抑制因子的作用交换了信息。讨论了NDP激酶α和β基因转导细胞获得的数据与其转移潜力的关系。

I.Signal transduction and NDP kinasePossible involvement of NDP kinase in those signal transduction systems has been originally proposed based on the observation that hormones can activate effector adenylyl cyclase in rat liver and human platelet membranes in the presence of GDP as observed for GTP.NDP kinase seems to act as a receptor activation-mediated GTP supply machinery for the G proteins in these signal transduction systems.The relationship between NDP kinase and signal transduction systems was further investigated by Dr.Orlov in TMIG using bovine retinal rod outer segment (ROS) preparations where components of signal transduction are extremely concentrated compared with other tissues.The soluble NDP kinase in the ROS preparations was found to interact with the ROS membranes in a pH,monovalent and divalent cations dependent manner.The NDP kinase bound to the membranes under acidic pH and low ionic strenght was released by the presence of GTP or its analogs (GTPgammaS,GppNHp).The results demonstrated that transducin (Gt) seems to be involved in the high affinity, GTP-sensitive interaction of the soluble NDP kinase with the bleached ROS membranes.II.Participation in the international workshop and visiting to NIHDrs.Kimura and Ishikawa participated in the first international workshop held in Paris at Pasteur Institute and gave talks entitled "The role of NDP kinases/nm23 in cellular functions "and" Rat NDP kinase isoform genes : structures and expression", respectively.It should be noted that Dr.Kimura chaired a session in the meeting.They then visited with Dr.Liotta at NIH in the U.S.to exchange information on the role of NDP kinase/nm23 as a candidate tumor metastasis suppressor.The data obtained with NDP kinase alpha- and beta-transfected cells in relation to their metastatic potential were discussed.