The Structure and Gating of the Epithelial Na+ Channel

上皮Na通道的结构和门控

• 批准号: 7008161
• 负责人: OSSAMA B KASHLAN
• 金额: $ 4.73万
• 依托单位: UNIVERSITY OF PITTSBURGH AT PITTSBURGH
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-07-01 至 2006-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7008161
• 关键词: Xenopus; Xenopus oocyte; allosteric site; binding sites; conformation; microinjections; physical model; postdoctoral investigator; protein folding; protein protein interaction; protein structure function; site directed mutagenesis; sodium channel; voltage /patch clamp; Xenopus; Xenopus oocyte; allosteric site; binding sites; conformation; microinjections; physical model; postdoctoral investigator; protein folding; protein protein interaction; protein structure function; site directed mutagenesis; sodium channel; voltage /patch clamp

DESCRIPTION (provided by applicant): Epithelial Na+ Channel (ENaC) activity can be modulated by two distinct mechanisms: either by changes in single channel gating properties (i.e., open probability), or by changes in the number of channels expressed in the apical membrane. The mechanism for ENaC gating has yet to be determined. Based on analogy with other cation channels, several mechanisms have been proposed. These mechanisms generally fall into two categories, either channel blocking, or an allosteric transition. In the channel-blocking hypothesis, either a portion of ENaC itself, or another molecule inserts into the channel pore, preventing Na+ transfer. In this hypothesis, changes in residue contacts as the channel transitions from an open to a closed state would be localized to the area, which interacts with the blocker. In the allosteric transition hypothesis, the helices, which form the pore, would undergo a conformational change such that Na+ could no longer traverse the pore. External stimuli could induce such a transition by causing small local changes, which could propogate into global changes, driving the allosteric transition. In this hypothesis, changes in residue contacts as the channel transitions from an open to a closed state would be widespread. We hypothesize that residue contacts made within the pore region of ENaC are altered in the open vs. the closed conformation of the channel. In order to assess these changes, we will exploit the ability of Ni2+ to selectively bind histidine to generate a map of pore region residues. Such a map will help to delineate which amongst the currently proposed models for ENaC gating is most likely

描述（由申请人提供）：上皮Na+通道（ENAC）活性可以通过两种不同的机制来调节：通过单个通道门控属性的变化（即开放概率），或者通过顶端膜中表达的通道数的变化。 ENAC门控机制尚未确定。基于与其他阳离子通道的类比，已经提出了几种机制。这些机制通常分为两类，要么是通道阻塞或变构转变。在通道阻断假说中，一部分ENAC本身或其他分子插入通道孔中，以防止Na+转移。在这一假设中，由于从开放状态到封闭状态的通道转变将定位到与阻滞剂相互作用的区域，因此残基接触的变化。在变构过渡假设中，形成孔的螺旋会发生构象变化，以使Na+不再能穿过孔。外部刺激可以通过造成局部较小的变化来引起这种过渡，这可能会导致全球变化，从而推动变构转变。在这一假设中，由于从开放状态向封闭状态的通道转变将被广泛分布，因此残基接触的变化将被广泛分布。我们假设在ENAC孔区域内进行的残留接触在开放式和通道的封闭构象中发生了变化。为了评估这些变化，我们将利用Ni2+选择性结合组氨酸以生成孔隙区域残基的图的能力。这样的地图将有助于描述哪些目前提出的ENAC门控模型很可能是