Studies of P2X ATP Receptors

P2 X蛋白是ATP门控通道，其使细胞脱钙并允许钙进入。P2x 受体在几乎所有组织中表达，包括中枢和外周的神经元和神经胶质。 神经系统，平滑，骨骼肌和心肌，耳蜗毛细胞，血小板，大多数类别为白色 血细胞、肝细胞以及肺和胃肠道中的内皮细胞。的重要性 该基因家族的成员对正常生理的影响从在 它们的缺失，其中特异性P2 X受体被敲除的小鼠显示疼痛感知功能障碍， 排空膀胱的能力，肠道运动，射精的神经元控制，神经系统的能力， 监测血液中的含氧量、抵抗细菌感染的能力和血液凝固。一个主要 嘌呤能受体领域的问题是可使用的激动剂和拮抗剂的有限特异性 来改变体内ATP信号。这里描述的实验的目标是更好地表征 允许ATP和变构调节剂打开P2 X受体通道的分子机制。结果 这些研究的结果应该有助于开发对特定受体没有更特异性作用的药物。 我们将利用电生理学、生物化学和分子生物学的方法来研究 相邻或不相邻亚基中的互补突变。具体目标是： 目标1-检测调节P2 X2、P2 X3和P2 X4中通道活性的锌结合位点是否 受体在亚基内或亚基之间，并定义参与这些结合位点的残基。我们 还将定义我们对锌促进P2 X2通道开放的机制的理解 受体。 目标2 -测试P2 X受体的ATP结合位点是否在亚基内或亚基之间，并确定 暴露在ATP结合口袋中的额外残基。这些实验也将检验 ATP分子必须结合才能打开通道。 目标3 -确定锌或ATP与P2 X2结合的分子运动 受体。 这些实验对于在理解和治疗疼痛方面取得进展具有特别的意义 与组织损伤相关，因为P2 X2和P2 X3受体被认为起着重要作用 感觉到损伤并向中枢神经系统发出信号。更好地了解 这些受体的结构应该允许开发这种类型疼痛的新治疗方法， 极大地减轻了烧伤和其他产生持续疼痛的伤害的个人的痛苦。

The P2X proteins are ATP gated channels that depolarize cells and also allow calcium to enter. P2X receptors are expressed in virtually every tissue, including neurons and glia of the central and peripheral nervous system, smooth, skeletal and cardiac muscle, cochlear hair cells, platelets, most classes of white blood cells, hepatocytes, and endothelial cells in the lung and gastrointestinal tract. The importance of members of this gene family for normal physiology is apparent from the range of phenotypes that are seen in their absence, Mice in which specific P2X receptors are knocked out show dysfunction in pain perception, ability to void the bladder, gut motility, neuronal control of ejaculation, the ability of the nervous system to monitor the oxygen level in the blood, the ability to fight bacterial infection, and blood clotting. A major problem in the purinergic receptor field is the limited specificity of agonists and antagonists that can be used to alter ATP signaling in vivo. The goal of the experiments described here is to better characterize the molecular mechanisms that allow ATP and allosteric modulators to open P2X receptor channels. The results of these studies should facilitate the development of agents tha't act more specifically on particular receptors. We will use electrophysiological, biochemical, and molecular approaches to study receptors bearing complementary mutations in adjacent or non-adjacent subunits. The specific aims are: Goal 1- To test whether the zinc binding sites that modulate channel activity in P2X2, P2X3, and P2X4 receptors are within or between subunits, and to define residues that participate in these binding sites. We will also define our understanding about the mechanisms by which zinc promotes channel opening in P2X2 receptors. Goal 2 - To test whether the ATP binding site of P2X receptors is within or between subunits and to define additional residues that are exposed in the ATP binding pocket. These experiments will also test the number of molecules of ATP that must be bound in order to open a channel. Goal 3 - To define the molecular movements that are a consequence of zinc or ATP binding to P2X2 receptors. These experiments are of particular relevance to making progress in understanding and treating pain associated with tissue injury, as P2X2 and P2X3 receptors have been implicated as playing essential roles as sensing the damage and signaling the central nervous system. Having a better understanding of the structure of these receptors should allow the development of new treatments for this type of pain, and so greatly ease the suffering of individuals with burns and other injuries that produce persistent pain.