Accessibility of Cations to the Selectivity Filter of KcsA in the Inactivated State: An Equilibrium Binding Study.

ABSTRACT: Cation binding under equilibrium conditions has been used as a tool to explore the accessibility of permeant and nonpermeant cations to the selectivity filter in three different inactivated models of the potassium channel KcsA. The results show that the stack of ion binding sites (S1 to S4) in the inactivated filter models remain accessible to cations as they are in the resting channel state. The inactivated state of the selectivity filter is therefore "resting-like" under such equilibrium conditions. Nonetheless, quantitative differences in the apparent KD's of the binding processes reveal that the affinity for the binding of permeant cations to the inactivated channel models, mainly K⁺, decreases considerably with respect to the resting channel. This is likely to cause a loss of K⁺ from

SUBMITTER: Giudici AM 

PROVIDER: S-EPMC6387330 | biostudies-literature | 2019 Feb

REPOSITORIES: biostudies-literature