Regulation of the Na/K Pump by RNA Editing

这项工作的长期目标是在分子和生物物理水平上了解RNA编辑如何调节离子通道和转运蛋白。通过腺苷脱氨基进行RNA编辑是一种 转录后的过程，对神经系统的正常功能至关重要。虽然已经证明许多信使核糖核酸底物被这种机制编辑，但人们对这些修饰的功能后果知之甚少。由于Na/K泵在离子动态平衡的调节中起着核心作用，因此本研究将Na/K泵作为膜蛋白的模型。 Pre-mRNAs中腺苷的酶促转化为肌苷(A-gt；I)允许多种蛋白质 来自单个基因的产物，从而扩展了生物体的基因组能力。这些 转化不是随机的，而是针对蛋白质中具有重要功能的区域。例如，在谷氨酸门控离子通道的GluRB亚单位中，编辑是通道孔道中Q到R转换的基础，GluRB亚单位对中枢神经系统中快速兴奋性突触传递非常重要。这种对生存至关重要的变化，使受体对钙离子不能通透。编辑的底物是通过比较同一基因的基因组和cDNA序列来鉴定的。在SQUID中，这一过程得到了极大的简化，因为编辑非常广泛。这项建议利用SQUID中的高级编辑来识别功能上相关的突变。

The long term objective of this work is to understand, at a molecular and biophysical level, how RNA editing regulates ion channels and transporters. RNA editing by adenosine deamination is a posttranscriptional process that is essential for proper nervous system function. Although many mRNA substrates have been shown to be edited by this mechanism, very little is known about the functional consequences of these modifications. This proposal focuses on the Na/K pump as a model membrane protein because it plays a central role in the regulation of ion homeostasis. The enzymatic conversion of adenosine to inosine (A -> I) in pre- mRNAs allows multiple protein products from a single gene, thereby extending the genomic capability of an organism. These conversions are not random, but are targeted to functionally important domains within the protein. For example, in the GluRB subunit of the glutamate-gated ion channel, important for fast excitatory synaptic transmission in the central nervous system, editing underlies the conversion of Q to R in the channel's pore. This change, which is essential for survival, renders the receptor impermeable to calcium ions. Edited substrates are identified by comparing genomic and cDNA sequences for the same gene. This process is greatly simplified in squid where editing is extensive. This proposal takes advantage of high level editing in squid to identify mutations that are functionally relevant.