RCSB PDB - 6CPV: MicroED structure of NaK ion channel reveals a process of Na+ partition into the selectivity filter

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MicroED structure of the NaK ion channel reveals a Na+partition process into the selectivity filter.

Liu, S., Gonen, T.

(2018) Commun Biol 1: 38-38

• PubMed: 30167468 Search on PubMedSearch on PubMed Central
• DOI: https://doi.org/10.1038/s42003-018-0040-8


• PubMed Abstract: 

  Sodium (Na ⁺ ) is a ubiquitous and important inorganic salt mediating many critical biological processes such as neuronal excitation, signaling, and facilitation of various transporters. The hydration states of Na ⁺ are proposed to play critical roles in determining the conductance and the selectivity of Na ⁺ channels, yet they are rarely captured by conventional structural biology means. Here we use the emerging cryo-electron microscopy (cryoEM) method micro-electron diffraction (MicroED) to study the structure of a prototypical tetrameric Na ⁺ -conducting channel, NaK, to 2.5 Å resolution from nano-crystals. Two new conformations at the external site of NaK are identified, allowing us to visualize a partially hydrated Na ⁺ ion at the entrance of the channel pore. A process of dilation coupled with Na ⁺ movement is identified leading to valuable insights into the mechanism of ion conduction and gating. This study lays the ground work for future studies using MicroED in membrane protein biophysics.

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Organizational Affiliation: 

Janelia Research Campus, Howard Hughes Medical Institute, 19700 Helix Drive, Ashburn, VA, 20147, USA.

• Method: ELECTRON CRYSTALLOGRAPHY
• Resolution: 2.50 Å
• R-Value Free:  0.263 (Depositor) 
• R-Value Work:  0.218 (Depositor) 
• R-Value Observed: 0.221 (Depositor)