神经末梢中钠钙交换体的化学计量学
Stoichiometry of the sodium-calcium exchanger in nerve terminals.
作者信息
Barzilai A, Rahamimoff H
机构信息
Department of Biochemistry, Hebrew University, Hadassah Medical School, Jerusalem, Israel.
出版信息
Biochemistry. 1987 Sep 22;26(19):6113-8. doi: 10.1021/bi00393a025.
The stoichiometry of the Na+-Ca2+ exchanger from synaptic plasma membranes was studied in both native and reconstituted preparations. In kinetic experiments performed with the native preparation, initial rates of Na+ gradient-dependent Ca2+ influx were compared to Ca2+-dependent Na+ efflux. These experiments showed that 4.82 Na+ ions are exchanged for each Ca2+ ion. A thermodynamic approach in which equilibrium measurements were made with the reconstituted preparation resulted in a similar (4.76) stoichiometry. The effects of membrane potential generated by valinomycin-induced K+ fluxes could be demonstrated in the reconstituted preparation. In addition, the direct contribution of the Na+-Ca2+ exchanger to the membrane potential across the reconstituted vesicle membrane could be demonstrated by using the lipophilic cation tetraphenylphosphonium.
在天然和重组制剂中研究了来自突触质膜的钠钙交换体的化学计量。在用天然制剂进行的动力学实验中，将钠梯度依赖性钙内流的初始速率与钙依赖性钠外流进行了比较。这些实验表明，每一个钙离子可交换4.82个钠离子。在重组制剂中进行平衡测量的热力学方法得出了相似的（4.76）化学计量。缬氨霉素诱导的钾通量产生的膜电位效应可在重组制剂中得到证明。此外，通过使用亲脂性阳离子四苯基鏻，可以证明钠钙交换体对重组囊泡膜跨膜电位的直接贡献。
Zotero 插件