Activation of recombinant mouse acetylcholine receptors by acetylcholine, carbamylcholine and tetramethylammonium.
Activation of recombinant mouse acetylcholine receptors by acetylcholine, carbamylcholine and tetramethylammonium.
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乙酰胆碱、氨甲酰胆碱和四甲基铵激活重组小鼠乙酰胆碱受体。
DOI：
10.1113/jphysiol.1995.sp020802
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发表时间：
1995
期刊：
影响因子：
--
通讯作者：
Auerbach,A
中科院分区：
文献类型：
--
作者：
Zhang,Y;Chen,J;Auerbach,A
1.在高浓度乙酰胆碱(ACh)、氨基甲酰胆碱(CCH)和四甲基铵(TMA)的作用下，研究了克隆的小鼠胚胎烟碱型乙酰胆碱受体(AChRs)在HEK 293细胞和非洲爪哇卵母细胞中表达的动力学特性。在一定的激动剂浓度范围内，通过将动力学模型与理想化的开放和闭合间隔进行拟合来估计激动剂结合和通道门控的速率常数。2.一旦双连接，TMA激活的受体以约3000 S-1的速度开放。TMA的平衡结合常数分别为525和12,800微米。双配体CCH激活的受体在约11,500 S-1处开放；该激动剂的平衡结合常数为14和570微米。如果我们假设双连接的ACh激活的受体在60,000 S-1处开放，则ACh的平衡结合常数为20和>；650微米，与CCH的结合常数相似。对于所有三种激动剂，高亲和力部位结合和释放激动剂的速度都慢于低亲和力部位。3.ACh和CCH分别以约2×10(7)和4×10(7)M~(-1)S-1的第一和第二结合位点与这两个位点结合。与ACh相比，TMA结合速率在第一结合部位大约慢100倍，在第二结合部位大约慢30倍。这些结果表明，TMA在这两个结合部位的结合率不受扩散或空间因素的限制。4.三种激动剂均以相似的速率从受体结合部位解离。所有激动剂在第一个结合部位的解离速度大约是在第二个结合部位的40倍。这些结果表明，季胺部分与受体的相互作用决定了激动剂的释放速度，并且这种相互作用的性质在两个结合部位有很大的不同。5.尽管三种激动剂的通道开放速率相差约20倍，但通道关闭速率并不强烈依赖于激动剂，而且相差不到3倍。我们推测，激动剂的酯部分促进了配体受体的快速结合和快速开放，而激动剂的季胺部分与受体的相互作用决定了通道关闭速率常数。
1. The kinetic properties of cloned mouse embryonic nicotinic acetylcholine receptors (AChRs) expressed in HEK 293 cells or Xenopus oocytes were examined using high concentrations of acetylcholine (ACh), carbamylcholine (CCh), or tetramethylammonium (TMA). The rate constants of agonist binding and channel gating were estimated by fitting kinetic models to idealized open and closed intervals over a range of agonist concentrations. 2. Once doubly liganded, TMA‐activated receptors open at approximately 3000 s‐1. The equilibrium binding constants for TMA are 525 and 12,800 microM. Doubly liganded CCh‐activated receptors open at approximately 11,500 s‐1; the equilibrium binding constants for this agonist are 14 and 570 microM. If we assume that doubly liganded, ACh‐activated receptors open at 60,000 s‐1, then the equilibrium binding constants for ACh are 20 and > 650 microM, similar to those for CCh. For all three agonists the higher affinity site both binds and releases agonists more slowly than does the lower affinity site. 3. ACh and CCh bind to the two sites equally rapidly, at approximately 2 x 10(7) and 4 x 10(7) M‐1 s‐1 at the first and second binding sites, respectively. Compared with ACh, the TMA association rate is approximately 100 times slower at the first binding site, and approximately 30 times slower at the second binding site. These results indicate that at both binding sites the association rate of TMA is not limited by diffusional or steric factors. 4. All three agonists dissociate from the receptor binding sites at similar rates. The dissociation rate for all agonists was approximately 40 times slower at the first binding site than at the second. These results suggest that the interaction of the quarternary amine moiety with the receptor determines the rate of release of the agonist, and that the nature of this interaction is quite different at the two binding sites. 5. Although the channel opening rates for the three agonists varied approximately 20‐fold, the channel closing rates were not strongly agonist dependent, and varied less than 3‐fold. We speculate that the ester moiety of the agonist promotes both rapid binding and fast opening of the ligand receptors, and that interactions of the quarternary amine moiety of the agonist with the receptor determine the channel closing rate constant.
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DOI：
10.1073/pnas.90.13.6285
发表时间：
1993-07-01
影响因子：
11.1
作者：
CZAJKOWSKI, C;KAUFMANN, C;KARLIN, A
通讯作者：
KARLIN, A
影响因子：
3.4
作者：
HORN, R;LANGE, K
通讯作者：
LANGE, K
DOI：
10.1073/pnas.86.7.2199
发表时间：
1989-04-01
影响因子：
11.1
作者：
JACKSON, MB
通讯作者：
JACKSON, MB
影响烟碱乙酰胆碱受体激动剂敏感性的突变。
影响因子：
3.4
作者：
Tomaselli,GF;McLaughlin,JT;Jurman,ME;Hawrot,E;Yellen,G
通讯作者：
Yellen,G
模型判别中的统计方法
影响因子：
2.1
作者：
P. Reilly
通讯作者：
P. Reilly