The Role of NDP kinases in Membrane Signal Transduction

I.信号转导和NDP激酶最初基于如下观察提出了NDP激酶在那些信号转导系统中的可能参与：如对GTP所观察到的，在GDP存在下，激素可以激活大鼠肝脏和人血小板膜中的效应腺苷酸环化酶。在这些信号转导系统中，NDP激酶是由GTP介导的G蛋白供应机制，奥尔洛夫博士在Tennessee使用牛视网膜杆进一步研究了NDP激酶与信号转导系统之间的关系细胞外段（ROS）是细胞膜上信号转导成分极为集中的部位，ROS中的可溶性NDP激酶与ROS膜的相互作用依赖于pH值、一价和二价阳离子，在酸性pH和低离子强度下结合于ROS膜上的NDP激酶在GTP或其类似物存在下释放结果表明，转导素（Gt）似乎参与了高亲和力，GTP-可溶性NDP激酶与漂白ROS膜的敏感相互作用。II.参加国际研讨会和访问NIHDrs Kimura和石川参加了在巴黎巴斯德举行的第一次国际研讨会研究所，并分别发表了题为“The role of NDP kinases/nm 23 in cellular functions“和”Rat NDP kinase isoform genes：structures and expression”的演讲。值得注意的是，Kimura博士在会议中主持了一个会议。然后，他们在www.example.com上与NIH的Liotta博士U.S.to交流了关于NDP kinase/nm 23作为候选肿瘤转移抑制因子的作用的信息。用NDP kinase alpha-和β-转染细胞的转移潜力进行了讨论。

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.