Structural basis of lipid-mediated gating in a two-pore domain potassium channel

TOK1 is the first identified member of the K2P channel family and contains additional N- and C-terminal domains, displaying a configuration distinct from that of canonical K2P channels. Although recent advances in structural studies of K2P channels have elucidated their architectures, the structural basis of TOK1 has remained unknown, limiting our understanding of its unique configuration. Here, we present the cryo-electron microscopy (cryo-EM) structure of TOK1, unveiling its distinctive domain architecture. Furthermore, the structures of TOK1 in three distinct states provide mechanistic insights into its regulation through lipid binding and dissociation. Phosphorylation of TOK1 induces the formation of an additional lipid-binding site, leading to channel inactivation. Conversely, upon activation, the phospholipid dissociates, allowing ion permeation. Our comprehensive study, integrating cryo-EM structural analysis, molecular dynamics simulations, electrophysiological recordings, and mass spectrometry, elucidates the distinctive features of TOK1, an atypical K2P channel, and provides a framework for understanding lipid-mediated regulation within this family.