Structure of the voltage-gated two-pore channel TPC1 from Arabidopsis thaliana

Nature. 2016 Mar 10;531(7593):196-201. doi: 10.1038/nature16446. Epub 2015 Dec 21.


Two-pore channels (TPCs) contain two copies of a Shaker-like six-transmembrane (6-TM) domain in each subunit and are ubiquitously expressed in both animals and plants as organellar cation channels. Here we present the crystal structure of a vacuolar two-pore channel from Arabidopsis thaliana, AtTPC1, which functions as a homodimer. AtTPC1 activation requires both voltage and cytosolic Ca(2+). Ca(2+) binding to the cytosolic EF-hand domain triggers conformational changes coupled to the pair of pore-lining inner helices from the first 6-TM domains, whereas membrane potential only activates the second voltage-sensing domain, the conformational changes of which are coupled to the pair of inner helices from the second 6-TM domains. Luminal Ca(2+) or Ba(2+) can modulate voltage activation by stabilizing the second voltage-sensing domain in the resting state and shift voltage activation towards more positive potentials. Our Ba(2+)-bound AtTPC1 structure reveals a voltage sensor in the resting state, providing hitherto unseen structural insight into the general voltage-gating mechanism among voltage-gated channels.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Arabidopsis / chemistry*
  • Arabidopsis Proteins / chemistry*
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism
  • Barium / metabolism
  • Binding Sites
  • Calcium / metabolism
  • Calcium / pharmacology
  • Calcium Channels / chemistry*
  • Calcium Channels / genetics
  • Calcium Channels / metabolism
  • Crystallography, X-Ray
  • Cytosol / metabolism
  • EF Hand Motifs
  • Electric Conductivity
  • HEK293 Cells
  • Humans
  • Ion Channel Gating / drug effects
  • Ion Transport / drug effects
  • Membrane Potentials / drug effects
  • Models, Molecular
  • Molecular Sequence Data
  • Protein Multimerization
  • Protein Structure, Quaternary
  • Protein Subunits / chemistry
  • Protein Subunits / metabolism


  • Arabidopsis Proteins
  • Calcium Channels
  • Protein Subunits
  • TPC1 protein, Arabidopsis
  • Barium
  • Calcium

Associated data

  • PDB/5E1J