Fig. 1: Structures of Kv4.2 alone and the Kv4.2–KChIP1, Kv4.2–DPP6S and Kv4.2–DPP6S–KChIP1 complexes.

a, Overall structures of the Kv4.2-alone tetramer, Kv4.2–KChIP1 octamer, Kv4.2–DPP6S octamer and Kv4.2–DPP6S–KChIP1 dodecamer (left to right). Four Kv4.2 subunits are coloured blue, four KChIP1 subunits are coloured yellow and four DPP6S subunits are coloured magenta. b, Structural comparison of the Kv4.2 N and C termini in the presence (right) and absence (left) of KChIP1. Protomers of Kv4.2 alone and three complexes are shown. Although both N and C termini are disordered in Kv4.2 alone and in the Kv4.2–DPP6S complex (left), both termini are resolved in the Kv4.2–KChIP1 and the Kv4.2–DPP6S–KChIP1 complexes (right). c, The intracellular S6 helix of Kv4.2 alone bends at the interface on the T1–S1 linker (dashed ellipse) and is subsequently disordered. By contrast, the S6 helix of the Kv4.2–KChIP1 complex extends straight toward KChIP1. d, Close-up view of the superimposed image in the dashed ellipse in c. The intracellular S6 of Kv4.2 starts bending from A419 and extend away from the T1–S1 linker in Kv4.2 alone and in the Kv4.2–DPP6S complex. However, it keeps a close distance to the T1–S1 linker without bending in the Kv4.2–KChIP1 and the Kv4.2–DPP6S–KChIP1 complexes.