Modulation of voltage-gated potassium (Kv) channels by auxiliary subunits is central to the physiological function of channels in the brain and heart^1,2. Native Kv4 tetrameric channels form macromolecular ternary complexes with two auxiliary β-subunits—intracellular Kv channel-interacting proteins (KChIPs) and transmembrane dipeptidyl peptidase-related proteins (DPPs)—to evoke rapidly activating and inactivating A-type currents, which prevent the backpropagation of action potentials^1,2,3,4,5. However, the modulatory mechanisms of Kv4 channel complexes remain largely unknown. Here we report cryo-electron microscopy structures of the Kv4.2–DPP6S–KChIP1 dodecamer complex, the Kv4.2–KChIP1 and Kv4.2–DPP6S octamer complexes, and Kv4.2 alone. The structure of the Kv4.2–KChIP1 complex reveals that the intracellular N terminus of Kv4.2 interacts with its C terminus that extends from the S6 gating helix of the neighbouring Kv4.2 subunit. KChIP1 captures both the N and the C terminus of Kv4.2. In consequence, KChIP1 would prevent N-type inactivation and stabilize the S6 conformation to modulate gating of the S6 helices within the tetramer. By contrast, unlike the reported auxiliary subunits of voltage-gated channel complexes, DPP6S interacts with the S1 and S2 helices of the Kv4.2 voltage-sensing domain, which suggests that DPP6S stabilizes the conformation of the S1–S2 helices. DPP6S may therefore accelerate the voltage-dependent movement of the S4 helices. KChIP1 and DPP6S do not directly interact with each other in the Kv4.2–KChIP1–DPP6S ternary complex. Thus, our data suggest that two distinct modes of modulation contribute in an additive manner to evoke A-type currents from the native Kv4 macromolecular complex.

辅助亚基对电压门控钾 (Kv) 通道的调节是大脑和心脏^1,2通道生理功能的核心。天然 Kv4 四聚体通道与两个辅助 β 亚基——细胞内 Kv 通道相互作用蛋白 (KChIPs) 和跨膜二肽基肽酶相关蛋白 (DPPs)——形成大分子三元复合物，以引发快速激活和失活的 A 型电流，从而防止反向传播动作电位^1,2,3,4,5. 然而，Kv4 通道复合物的调节机制仍然很大程度上未知。在这里，我们报告了 Kv4.2–DPP6S–KChIP1 十二聚体复合物、Kv4.2–KChIP1 和 Kv4.2–DPP6S 八聚体复合物以及单独的 Kv4.2 的低温电子显微镜结构。Kv4.2-KChIP1 复合物的结构表明，Kv4.2 的细胞内 N 末端与其从相邻 Kv4.2 亚基的 S6 门控螺旋延伸的 C 末端相互作用。KChIP1 捕获 Kv4.2 的 N 和 C 末端。因此，KChIP1 将阻止 N 型失活并稳定 S6 构象以调节四聚体内 S6 螺旋的门控。相比之下，与报道的电压门控通道复合物的辅助亚基不同，DPP6S 与 Kv4.2 电压感应域的 S1 和 S2 螺旋相互作用，这表明 DPP6S 稳定了 S1-S2 螺旋的构象。因此，DPP6S 可以加速 S4 螺旋的电压依赖性运动。KChIP1 和 DPP6S 在 Kv4.2–KChIP1–DPP6S 三元复合物中不直接相互作用。因此，我们的数据表明，两种不同的调制模式以相加的方式有助于从天然 Kv4 大分子复合物中唤起 A 型电流。