National Institutes of Health/Office of the Director
DP5OD017871
米国
American Heart Association
19TPA34760754
米国
American Heart Association
18PRE33990205
米国
National Science Foundation (NSF, United States)
DGE-1937961
米国
引用
ジャーナル: Elife / 年: 2020 タイトル: Molecular principles of assembly, activation, and inhibition in epithelial sodium channel. 著者: Sigrid Noreng / Richard Posert / Arpita Bharadwaj / Alexandra Houser / Isabelle Baconguis / 要旨: The molecular bases of heteromeric assembly and link between Na self-inhibition and protease-sensitivity in epithelial sodium channels (ENaCs) are not fully understood. Previously, we demonstrated ...The molecular bases of heteromeric assembly and link between Na self-inhibition and protease-sensitivity in epithelial sodium channels (ENaCs) are not fully understood. Previously, we demonstrated that ENaC subunits - α, β, and γ - assemble in a counterclockwise configuration when viewed from outside the cell with the protease-sensitive GRIP domains in the periphery (Noreng et al., 2018). Here we describe the structure of ENaC resolved by cryo-electron microscopy at 3 Å. We find that a combination of precise domain arrangement and complementary hydrogen bonding network defines the subunit arrangement. Furthermore, we determined that the α subunit has a primary functional module consisting of the finger and GRIP domains. The module is bifurcated by the α2 helix dividing two distinct regulatory sites: Na and the inhibitory peptide. Removal of the inhibitory peptide perturbs the Na site via the α2 helix highlighting the critical role of the α2 helix in regulating ENaC function.