Conformations of Torpedo acetylcholine receptor associated with ion transport and desensitization.
Conformations of Torpedo acetylcholine receptor associated with ion transport and desensitization.
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鱼雷乙酰胆碱受体的构象与离子转运和脱敏相关。
DOI：
10.1021/bi00257a032
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发表时间：
1982
期刊：
影响因子：
2.9
通讯作者：
Cohen,JB
中科院分区：
文献类型：
--
作者：
Neubig,RR;Boyd,ND;Cohen,JB
Richard R.诺曼·诺伊比格博伊德和乔纳森B。Cohen* 摘要：在相同条件下，用快速混合技术测定了[3 ~* H]乙酰胆碱（AcCh）与离体电鳐电组织突触后膜烟碱受体结合的动力学和AcCh诱导的~（22）Na ~+从囊泡中流出的动力学。结合研究确定了导致受体构象以高亲和力结合AcCh的缓慢构象转变的速率常数ks [Kd= 2nM，fcdis= 0.04s-1，在4 ℃下][Boyd，N. D、和Cohen，JB（1980）Biochemistry 19，5344-5353，5353-5358]]。对于浓度在0.1和15 µ之间的AcCh，ks的特征在于希尔系数为1，（&s）max~ 0.8 s-1，10 µ AcCh产生半最大速率。在24 ms ~ 1000 s的时间范围内测量22 Na+流出，确定了22 Na+流出的初始速率（速率常数k 0，与开放通道数成比例的参数）和脱敏速率常数kd。测定了以下物质的kd值：
Richard R. Neubig, Norman D. Boyd, and Jonathan B. Cohen* abstract: Rapid-mixing techniques have been used to measure under identical conditions both the kinetics of binding of [3* H] acetylcholine (AcCh) to nicotinic receptors in postsy-naptic membranes isolated from Torpedo electric tissue and the kinetics of AcCh-induced efflux of 22Na+ from the vesicles. The binding studies define the rate constant, ks, of the slow conformational transition resulting in the receptor conformation binding AcCh with high affinity [Kd= 2 nM, fcdis= 0.04 s'1 at 4 C [Boyd, N. D., & Cohen, JB (1980) Biochemistry 19, 5344-5353, 5353-5358]]. For AcCh concen-trations between 0.1 and 15 µ, ks was characterized by a Hill coefficient of 1,(&s) max~ 0.8 s'1, and 10 µ AcCh produced a half-maximal rate. The observed 22Na+ efflux, measured at times from 24 ms to 1000 s, defined the initial rate of 22Na+ efflux (rateconstant, k0, a parameter propor-tional to the number of open channels) and a rate constant (kd) for desensitization. Values of kd were determined for