Lauffer L, Hucho F
Proc Natl Acad Sci U S A. 1982 Apr;79(7):2406-9. doi: 10.1073/pnas.79.7.2406.
The lipophilic cation triphenylmethylphosphonium (Ph3MeP+), which is widely used as a sensor for membrane potential with cells, organelles, and membrane vesicles, is shown also to accumulate in membranes rich in nicotinic acetylcholine receptor in a voltage-independent way. Evidence is presented that Ph3MeP+ in this system is bound to a cation-binding site of the ion channel that is part of the acetylcholine receptor complex. Binding is stimulated by cholinergic effectors (Kd = 13 microM in the absence of carbamoylcholine; Kd = 1.5 microM in the presence of 10 microM carbamoylcholine), and this stimulation is blocked by alpha-bungarotoxin. Ph3MeP+ blocks efflux of 22Na from receptor-rich microsacs and appears to compete with the channel ligand phencyclidine for a common binding site. In contrast to the binding of other proven channel ligands, Ph3MeP+-binding is not affected by desensitization.
亲脂性阳离子三苯基甲基鏻(Ph3MeP+)广泛用作细胞、细胞器和膜泡膜电位的传感器,研究表明它也能以电压非依赖的方式在富含烟碱型乙酰胆碱受体的膜中积累。有证据表明,该系统中的Ph3MeP+与乙酰胆碱受体复合物中离子通道的阳离子结合位点结合。胆碱能效应物可刺激这种结合(在没有氨甲酰胆碱的情况下,Kd = 13 μM;在存在10 μM氨甲酰胆碱的情况下,Kd = 1.5 μM),并且这种刺激可被α-银环蛇毒素阻断。Ph3MeP+可阻断富含受体的微囊泡中22Na的外流,并且似乎与通道配体苯环己哌啶竞争一个共同的结合位点。与其他已证实的通道配体的结合不同,Ph3MeP+的结合不受脱敏的影响。