Xu J, Yu W, Jan Y N, Jan L Y, Li M
Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
J Biol Chem. 1995 Oct 20;270(42):24761-8. doi: 10.1074/jbc.270.42.24761.
Voltage-gated potassium (K+) channels are assembled by four identical or homologous alpha-subunits to form a tetrameric complex with a central conduction pore for potassium ions. Most of the cloned genes for the alpha-subunits are classified into four subfamilies: Kv1 (Shaker), Kv2 (Shab), Kv3 (Shaw), and Kv4 (Shal). Subfamily-specific assembly of heteromeric K+ channel complexes has been observed in vitro and in vivo, which contributes to the diversity of K+ currents. However, the molecular codes that mediate the subfamily-specific association remain unknown. To understand the molecular basis of the subfamily-specific assembly, we tested the protein-protein interactions of different regions of alpha-subunits. We report here that the cytoplasmic NH2-terminal domains of Kv1, Kv2, Kv3, and Kv4 subfamilies each associate to form homomultimers. Using the yeast two-hybrid system and eight K+ channel genes, two genes (one isolated from rat and one from Drosophila) from each subfamily, we demonstrated that the associations to form heteromultimers by the NH2-terminal domains are strictly subfamily-specific. These subfamily-specific associations suggest a molecular basis for the selective formation of heteromultimeric channels in vivo.
电压门控钾离子（K+）通道由四个相同或同源的α亚基组装而成，形成一个具有钾离子中央传导孔的四聚体复合物。大多数已克隆的α亚基基因被分为四个亚家族：Kv1（震颤器）、Kv2（沙巴）、Kv3（肖）和Kv4（沙尔）。在体外和体内均观察到异源多聚体K+通道复合物的亚家族特异性组装，这有助于K+电流的多样性。然而，介导亚家族特异性关联的分子编码仍然未知。为了理解亚家族特异性组装的分子基础，我们测试了α亚基不同区域之间的蛋白质-蛋白质相互作用。我们在此报告，Kv1、Kv2、Kv3和Kv4亚家族的细胞质NH2末端结构域各自结合形成同源多聚体。使用酵母双杂交系统和八个K+通道基因，每个亚家族各两个基因（一个从大鼠中分离，一个从果蝇中分离），我们证明了NH2末端结构域形成异源多聚体的结合严格具有亚家族特异性。这些亚家族特异性关联为体内异源多聚体通道的选择性形成提供了分子基础。
