SULFONYLUREA RECEPTORS AND KATP CHANNELS

描述：(申请人摘要) ATP敏感钾通道(KATP通道)将代谢偶联到膜上 电活动。在胰岛β细胞中，KATP通道改变细胞膜 对葡萄糖引起的ATP/ADP比率变化的反应潜力 新陈代谢。为了了解KATP通道的功能，我们克隆了 重组了它们，表征了两组编码它们的人类基因 亚基、磺脲受体(SURS)和内向整流子(KIR6.x) 结果表明，SUR1和KIR6.2的突变导致隐性遗传 家族性高胰岛素血症。子单元功能紧密集成， 两者都是组装、调节和表面表达所必需的 异构体(SUR1/KIR6.2)4通道；单独表达的亚基保留在 急诊室。KIR6.2的C端截断去除了ER保留信号，从而 对ATP具有低敏感性的K+通道的表面表达，高度修饰 KATP通道的动力学和非药理学特性。 与SUR1的共表达在很大程度上恢复了原生通道属性。 SUR1和N端截断的KIR6.2的共同表达给出了一个具有 极大地延长了突发时间，降低了对ATP的敏感性。β细胞(SUR1)和 心脏(SUR2A)通道亚型表现出不同的动力学和ATP 敏感度。SURR嵌合体被用来识别两个区域，这些区域 动力学和三磷酸腺苷敏感性差异。这些结果开始定义一个 将未知的三磷酸腺苷结合位点放置在 KIR6.2是SuR的两个胞内片段，以及KIR6.2的N端。 紧靠海峡入海口。扰乱这一网络 相互作用可能以复杂的方式影响ATP抑制门控。 在此次竞争更新中，我们建议定义以下内容中的交互 使用肽展示、哺乳动物双杂交和表位标签的网络 识别所涉及的多肽片段的技术。具体来说，我们 假设存在以下相互作用：1)TMD1跨膜区 KIR6.2和SUR的TMD，2)KIR6.2的N端和其内的一段 SUR的第一组TMD，3)SUR的C末端和最后36个氨基酸 KIR6.2的氨基酸，以及4)SURR的最后52个氨基酸和C-末端 KIR6.2的细胞质结构域。

DESCRIPTION: (Applicant's Abstract) ATP-sensitive potassium channels (KATP channels) couple metabolism to membrane electrical activity. In pancreatic beta-cells KATP channels alter the membrane potential in response to changes in the ATP/ADP ratio driven by glucose metabolism. To understand how KATP channels function, we cloned and reconstituted them, characterized two sets of human genes that encode their subunits, sulfonylurea receptors (SURs) and inward rectifiers (KIR6.x) respectively, and showed that mutations in SUR1 and KIR6.2 cause a recessive form of familial hyperinsulinism. The subunit functions are tightly integrated, both are required for assembly, regulation and surface expression of the heteromeric (SUR1/KIR6.2)4 channel; subunits expressed alone are retained in the ER. C-terminal truncation of KIR6.2 removes an ER retention signal allowing surface expression of a K+ channel with low sensitivity to ATP, highly modified kinetics and none of the pharmacological properties of KATP channels. Co-expression with SUR1 largely restores the native channel properties. Co-expression of SUR1 with N-terminally truncated KIR6.2 gives a channel with greatly prolonged bursts and reduced ATP sensitivity. beta-cell (SUR1) and cardiac (SUR2A) channel isoforms exhibit different kinetics and ATP sensitivity. SUR chimeras have been used to identify two regions that specify the kinetic and ATP sensitivity differences. These results begin to define a web or network of interactions that place an unidentified ATP-binding site on KIR6.2, two intracellular segments of SUR, and the N-terminus of KIR6.2 in close proximity to the mouth of the channel. Disruption of this network of interactions can affect ATP-inhibitory gating in complex ways. In this competitive renewal we propose to define the interactions within this network using peptide display, mammalian two hybrid, and epitope tagging techniques to identify the peptide segments involved. Specifically we hypothesize there are interactions between: 1) Transmembrane domain 1 (TMD1) of KIR6.2 and the TMDs of SUR, 2) the N-terminus of KIR6.2 and a segment within the first set of TMDs of SUR, 3) the C-terminus of SUR and the last 36 amino acids of KIR6.2, and 4) the last 52 amino acids of SUR and the C-terminal cytoplasmic domain of KIR6.2.