Structural plasticity of the selectivity filter in a nonselective ion channel

The sodium potassium ion channel (NaK) is a nonselective ion channel that conducts both sodium and potassium across the cellular membrane. A new crystallographic structure of NaK reveals conformational differences in the residues that make up the selectivity filter between the four subunits that form the ion channel and the inner helix of the ion channel. The crystallographic structure also identifies a side-entry, ion-conduction pathway for Na+ permeation that is unique to NaK. NMR studies and molecular dynamics simulations confirmed the dynamical nature of the top part of the selectivity filter and the inner helix in NaK as also observed in the crystal structure. Taken together, these results indicate that the structural plasticity of the selectivity filter combined with the dynamics of the inner helix of NaK are vital for the efficient conduction of different ions through the non-selective ion channel of NaK.

Automated summary

The crystallographic study of the sodium potassium ion channel (NaK) identified differences in conformation of the selectivity filter and inner helix among the four subunits forming the ion channel. The study also revealed a unique side-entry ion-conduction pathway for Na+ permeation in NaK. Additionally, NMR and molecular dynamics simulations confirmed the dynamic nature of the selectivity filter and inner helix, highlighting their importance in efficient ion conduction through the non-selective ion channel of NaK.