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。通过腺苷脱氨进行RNA编辑是一种 转录后过程是神经系统正常功能所必需的。虽然许多mRNA底物已被证明是通过这种机制编辑的，但对这些修饰的功能后果知之甚少。该建议侧重于Na/K泵作为模型膜蛋白，因为它在离子稳态的调节中起着核心作用。 前体mRNA中腺苷酶促转化为肌苷（A -> I）允许多个蛋白质在mRNA中的表达。 从一个单一的基因产物，从而扩大了生物体的基因组能力。这些 转换不是随机的，而是靶向蛋白质内功能重要的结构域。例如，在谷氨酸门控离子通道的GluRB亚基中，对中枢神经系统中的快速兴奋性突触传递很重要，编辑是通道孔中Q转化为R的基础。这种对生存至关重要的变化使受体对钙离子不可渗透。通过比较相同基因的基因组和cDNA序列来鉴定编辑的底物。这个过程在squid中大大简化，因为编辑是广泛的。该提案利用鱿鱼中的高水平编辑来识别功能相关的突变。

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.