Structural Titration of Slo2.2, a Na⁺-Dependent K⁺ Channel.

ABSTRACT: The stable structural conformations that occur along the complete reaction coordinate for ion channel opening have never been observed. In this study, we describe the equilibrium ensemble of structures of Slo2.2, a neuronal Na⁺-activated K⁺ channel, as a function of the Na⁺ concentration. We find that Slo2.2 exists in multiple closed conformations whose relative occupancies are independent of Na⁺ concentration. An open conformation emerges from an ensemble of closed conformations in a highly Na⁺-dependent manner, without evidence of Na⁺-dependent intermediates. In other words, channel opening is a highly concerted, switch-like process. The midpoint of the structural titration matches that of the functional titration. A maxim

SUBMITTER: Hite RK 

PROVIDER: S-EPMC5382815 | biostudies-literature | 2017 Jan

REPOSITORIES: biostudies-literature