ION CHANNEL

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 门控是钾通道的主要调节模式;刺激改变离子孔的开放和闭合状态之间的平衡，使离子流过通道。KcsA通道（闭合状态）和MthK通道（开放状态）的结构揭示了这两种门控状态的分子特征，但我们仍然不清楚刺激如何引起构象变化。我们正在研究由cAMP门控的钾通道的结构测定。我们最近已经确定了它的监管结构域在绑定和未绑定的构象的结构，这种结构提供了有趣的和重要的见解，发生在配体结合后的水平上的环状核苷酸结合结构域的构象变化，并导致我们提出了一个模型通道门控。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个假定的跨膜片段（TM）;最后2个TM形成了离子传导途径，首次通过KcsA钾通道的结构揭示;在C末端有一个约150个残基的细胞质环状核苷酸结合结构域。 目前，我们正处于晶体筛选阶段，并已确定条件，以获得晶体的行为，以8 <$&。我们需要使用beamtime来继续筛选在不同洗涤剂条件下出现的晶体。

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.