Investigation of the α1-glycine receptor channel-opening kinetics in the submillisecond time domain
Investigation of the α1-glycine receptor channel-opening kinetics in the submillisecond time domain
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DOI：
10.1016/s0006-3495(99)76927-4
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发表时间：
1999-08-01
影响因子：
3.4
通讯作者：
Grewer, C
中科院分区：
文献类型：
--
作者：
Grewer, C
人α（1）-homooligomeric甘氨酸受体，这是在HEK 293细胞中瞬时表达的激活和脱敏动力学进行了研究，以确定单个受体反应步骤的速率和平衡常数与100 μ s的时间分辨率。激活配体甘氨酸和β-丙氨酸的浓度跳跃开始由笼，无活性的前体的光解，然后由神经递质结合，受体通道开放，受体脱敏的步骤，分离沿着时间轴。对这些过程的配体浓度依赖性的分析允许确定：I）甘氨酸结合的速率常数，k（+1）类似于10（7）M-1 s（-1），解离的速率常数，k（-1）= 1900 s（-1）; 2）受体通道打开的速率，k（op）= 2200 s（-1），和关闭的速率，k（cl）= 38 s（-1）; 3）受体脱敏率，α = 0.45 s（-1）; 4）受体通道激活和脱敏所需的被占据的配体结合位点的数量，n大于或等于3;和5）最大受体通道开放概率，rho（o）> 0.95。受体通道激活的动力学对跨膜电位不敏感。甘氨酸受体激活的一般模型解释的实验数据由一个连续的机制的基础上快速配体结合步骤之前的限速受体通道开放反应和缓慢的受体脱敏。
The activation and desensitization kinetics of the human alpha(1)-homooligomeric glycine receptor, which was transiently expressed in HEK 293 cells, were studied with a 100-mu s time resolution to determine the rate and equilibrium constants of individual receptor reaction steps. Concentration jumps of the activating ligands glycine and beta-alanine were initiated by photolysis of caged, inactive precursors and were followed by neurotransmitter binding, receptor-channel opening, and receptor desensitization steps that were separated along the time axis. Analysis of the ligand concentration-dependence of these processes allows the determination of I) the rate constants of glycine binding, k(+1) similar to 10(7) M-1 s(-1), and dissociation, k(-1) = 1900 s(-1); 2) the rates of receptor-channel opening, k(op) = 2200 s(-1), and closing, k(cl) = 38 s(-1); 3) the receptor desensitization rate, alpha = 0.45 s(-1); 4) the number of occupied ligand binding sites necessary for receptor-channel activation and desensitization, n greater than or equal to 3; and 5) the maximum receptor-channel open probability, rho(o) > 0.95. The kinetics of receptor-channel activation are insensitive to the transmembrane potential. A general model for glycine receptor activation explaining the experimental data consists of a sequential mechanism based on rapid ligand-binding steps preceding a rate-limiting receptor-channel opening reaction and slow receptor desensitization.