Ruppersberg J P, Schröter K H, Sakmann B, Stocker M, Sewing S, Pongs O
Max-Planck-Institut für medizinische Forschung, Abteilung Zellphysiologie, Heidelberg, FRG.
Nature. 1990 Jun 7;345(6275):535-7. doi: 10.1038/345535a0.
An important step towards understanding the molecular basis of the functional diversity of voltage-gated K+ channels in the mammalian brain has been the discovery of a family of genes encoding rat brain K+ channel-forming (RCK) proteins. All species of these RCK proteins form homomultimeric voltage-gated K+ channels with distinct functional characteristics in Xenopus laevis oocytes following injection of the respective cRNAs. RCK-specific mRNAs are coexpressed in several regions of the brain, suggesting that RCK proteins also assemble into heteromultimeric K+ channels. In addition expression experiments with fractionated poly(A)+ mRNA have suggested that heteromultimeric K+ channels may occur in mammalian brain. We report here that heteromultimeric K+ channels composed of two different RCK proteins (RCK1 and RCK4) assemble after cotransfection of HeLa cells with the corresponding cDNAs and after coinjection of the corresponding cRNAs into Xenopus oocytes. The heteromultimeric RCK1, 4 channel mediates a transient potassium outward current, similar to the RCK4 channel but inactivates more slowly, has a larger conductance and is more sensitive to block by dendrotoxin and tetraethylammonium chloride.
在理解哺乳动物大脑中电压门控钾通道功能多样性的分子基础方面，重要的一步是发现了一个编码大鼠脑钾通道形成（RCK）蛋白的基因家族。在注射各自的cRNA后，所有这些RCK蛋白在非洲爪蟾卵母细胞中形成具有不同功能特征的同多聚体电压门控钾通道。RCK特异性mRNA在大脑的几个区域共表达，这表明RCK蛋白也组装成异多聚体钾通道。此外，用分级分离的聚腺苷酸加尾mRNA进行的表达实验表明，异多聚体钾通道可能存在于哺乳动物大脑中。我们在此报告，由两种不同的RCK蛋白（RCK1和RCK4）组成的异多聚体钾通道，在将HeLa细胞与相应的cDNA共转染后以及将相应的cRNA共注射到非洲爪蟾卵母细胞后组装而成。异多聚体RCK1、4通道介导瞬时钾外向电流，类似于RCK4通道，但失活更慢，电导更大，对树突毒素和四乙铵氯化物的阻断更敏感。
