Wang H, Kunkel D D, Martin T M, Schwartzkroin P A, Tempel B L
Geriatric Research Education and Clinical Centre 182-B, Veterans Affairs Medical Center, Seattle, Washington 98108.
Nature. 1993 Sep 2;365(6441):75-9. doi: 10.1038/365075a0.
Voltage-gated potassium (K+) channels display a wide variety of conductances and gating properties in vivo. This diversity can be attributed not only to the presence of many K(+)-channel gene products, but also to the possibility that different K(+)-channel subunits co-assemble to form heteromultimeric channels in vivo. When expressed in Xenopus oocytes or transfected cells, K(+)-channel polypeptides assemble to form tetramers. Certain combinations of Shaker-like subunits have been shown to co-assemble, forming heteromultimeric channels with distinct properties. It is not known, however, whether K(+)-channel polypeptides form heteromultimeric channels in vivo. Here we describe the co-localization of two Shaker-like voltage-gated K(+)-channel proteins, mKv1.1 and mKv1.2, in the juxtaparanodal regions of nodes of Ranvier in myelinated axons, and in terminal fields of basket cells in mouse cerebellum. We also show that mKv1.1 and mKv1.2 can be coimmunoprecipitated with specific antibodies that recognize only one of them. These data indicate that the two polypeptides occur in subcellular regions where rapid membrane repolarization may be important and that they form heteromultimeric channels in vivo.
电压门控钾（K+）通道在体内表现出多种电导和门控特性。这种多样性不仅可归因于许多K+通道基因产物的存在，还可能是因为不同的K+通道亚基在体内共同组装形成异源多聚体通道。当在非洲爪蟾卵母细胞或转染细胞中表达时，K+通道多肽组装形成四聚体。已证明某些类似Shaker的亚基组合能够共同组装，形成具有独特特性的异源多聚体通道。然而，尚不清楚K+通道多肽在体内是否形成异源多聚体通道。在此，我们描述了两种类似Shaker的电压门控K+通道蛋白mKv1.1和mKv1.2在有髓轴突郎飞结旁结区域以及小鼠小脑篮状细胞终末场中的共定位。我们还表明，mKv1.1和mKv1.2可以用仅识别其中一种的特异性抗体进行共免疫沉淀。这些数据表明，这两种多肽存在于快速膜复极化可能很重要的亚细胞区域，并且它们在体内形成异源多聚体通道。
