Arispe N, De Mazancourt P, Rojas E
Laboratory of Cell Biology and Genetics, NIDDK, National Institutes of Health, Bethesda, MD 20892, USA.
J Membr Biol. 1995 Sep;147(2):109-19. doi: 10.1007/BF00233540.
We report here the presence of a Ca(2+)-independent K(+)-channel of large conductance in adrenal chromaffin cell secretory vesicle membranes which is controlled by inhibitory as well as stimulatory heterotrimeric GTP-binding proteins. Using antibodies against specific alpha subunits for immunoblot analysis, we were able to identify the presence of the inhibitory G(i)2 and G(i)3 subtypes, as well as the stimulatory G(o) and Gs subtypes, but not G(i)1 in adrenal chromaffin granules. Furthermore, functional analysis of the K(+)-channel incorporated into planar lipid bilayers showed that GDP beta S and GTP gamma S have opposite effects on channel activity inducing interconversions between a low and a high open-probability state. Consistent with these findings, the same antibodies antagonized the effects of the nonhydrolyzable analogues on the open probability of the K(+)-channel.
我们在此报告，肾上腺嗜铬细胞分泌囊泡膜中存在一种大电导的、不依赖钙离子的钾通道，该通道受抑制性和刺激性异源三聚体GTP结合蛋白调控。通过使用针对特定α亚基的抗体进行免疫印迹分析，我们能够鉴定出肾上腺嗜铬颗粒中存在抑制性G(i)2和G(i)3亚型，以及刺激性G(o)和Gs亚型，但不存在G(i)1。此外，对整合到平面脂质双分子层中的钾通道进行功能分析表明，GDPβS和GTPγS对通道活性有相反的影响，可诱导通道在低开放概率状态和高开放概率状态之间相互转换。与这些发现一致，相同的抗体可拮抗不可水解类似物对钾通道开放概率的影响。
