ION CHANNEL

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 门控是钾通道的主要调节模式；刺激改变了离子孔开放和关闭状态之间的平衡，让离子流过通道。KCSA通道(关闭状态)和MthK通道(开放状态)的结构揭示了这两个门控状态的分子特征，但我们仍然不清楚刺激是如何引起构象变化的。我们正在研究cAMP门控的钾通道的结构。我们最近确定了它在结合和非结合构象中的调节域的结构；这种结构为配体结合时环核苷酸结合域水平上发生的构象变化提供了有趣和重要的见解，并导致我们提出了一个通道门控模型。我们现在正在表达和生长全长通道的晶体。这种四聚体膜蛋白每个亚基有6个跨膜片段，最后2个跨膜片段形成离子传导途径，首先由KCSA钾通道的结构揭示；在C末端有一个~150个残基的细胞质环核苷酸结合域。 目前，我们正处于晶体筛选阶段，已经确定了获得衍射率为8°的晶体的条件。我们需要进入波束时间来继续筛选在不同洗涤剂中条件下出现的晶体。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Gating is the major mode of regulation of potassium channels; stimuli alter the equilibrium between the open and closed states of the ion pore letting ions flow through the channel. The structures of the KcsA channel (closed state) and the MthK channel (open state) revealed the molecular characteristics of the two gating states but we still do not understand clearly how stimuli induce the conformational change. We are working on the structure determination of a potassium channel that is gated by cAMP. We have recently determined the structure of its regulatory domain in both the bound and unbound conformations; this structure has provide interesting and important insights to the conformational changes that occur at the level of the cyclic-nucleotide binding domain upon ligand binding and has led us to proposed a model for channel gating. We are now expressing and growing crystals of the full-length channel. This tetrameric membrane protein has 6 putative transmembrane segments (TMs) per subunit; the last 2 TMs form the ion conduction pathway first revealed by the structure of the KcsA potassium channel; at the C-terminus there is a ~150 residue cytoplasmic cyclic-nucleotide binding domain. Presently, we are at the crystal screening stage and have already determined conditions to obtain crystals that diffract to 8¿¿¿ . We need access to beamtime to continue screening crystals that are emerging from conditions in different detergents.