The I182 region of k(ir)6.2 is closely associated with ligand binding in K(ATP) channel inhibition by ATP.
The I182 region of k(ir)6.2 is closely associated with ligand binding in K(ATP) channel inhibition by ATP.
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k(ir)6.2 的 I182 区域与 ATP 抑制 K(ATP) 通道中的配体结合密切相关。
DOI：
10.1016/s0006-3495(00)76340-5
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发表时间：
2000
影响因子：
3.4
通讯作者：
Drain,P
中科院分区：
文献类型：
--
作者：
Li,L;Wang,J;Drain,P
atp抑制钾（KATP）通道由四个向内整流钾（Kir6.x）亚基和四个磺酰脲受体（SURx）亚基组装而成。ATP的抑制作用是由Kir6.2的c端胞质尾部至少两个不同的功能域介导的。Kir6.2的G334D突变几乎消除了ATP依赖性门控，而对配体非依赖性门控没有影响，这表明该位点与门控的连接或ATP结合位点本身起作用。Kir6.2的T171A突变强烈破坏atp依赖性和配体非依赖性门控，表明T171在门控步骤中起作用。邻近的突变I182Q实际上消除了ATP抑制，但其对不依赖配体的门控的影响尚不清楚。我们现在已经描述了ATP抑制的kivalue和182位15个取代的与配体无关的门控动力学。所有取代都降低了ki测量的atp依赖性抑制门控，许多都是如此，但对配体非依赖性门控动力学几乎没有影响。因此，182位的取代不太可能通过破坏抑制门运动而起作用。我们的研究结果表明，I182在ATP结合机制的一个步骤中，在ATP结合位点与抑制门耦合的连锁机制中，或两者兼而有之，发挥着不可或缺的作用。
The ATP-inhibited potassium (KATP) channel is assembled from four inward rectifier potassium (Kir6.x) subunits and four sulfonylurea receptor (SURx) subunits. The inhibitory action of ATP is mediated by at least two distinct functional domains within the C-terminal cytoplasmic tail of Kir6.2. The G334D mutation of Kir6.2 virtually eliminates ATP-dependent gating with no effect on ligand-independent gating, suggesting a role in linkage of the site to the gate or in the ATP binding site, itself. The T171A mutation of Kir6.2 strongly disrupts both ATP-dependent and ligand-independent gating, suggesting a role for T171 in the gating step. A neighboring mutation, I182Q, virtually eliminates ATP inhibition, but its effect on ligand-independent gating remained unknown. We have now characterized both theKivalues for inhibition by ATP and the ligand-independent gating kinetics of 15 substitutions at position 182. All substitutions decreased ATP-dependent inhibition gating as measured by theKi, many profoundly so, yet had little or no effect on ligand-independent gating kinetics. Thus, substitutions at position 182 are unlikely to act by disrupting inhibition gate movement. Our results indicate an indispensable role for I182 in a step of the ATP binding mechanism, the linkage mechanism coupling the ATP binding site to the inhibition gate, or both.