CaT1 manifests the pore properties of the calcium-release-activated calcium channel

Nature. 2001 Apr 5;410(6829):705-9. doi: 10.1038/35070596.


The calcium-release-activated Ca2+channel, ICRAC, is a highly Ca2+-selective ion channel that is activated on depletion of either intracellular Ca2+ levels or intracellular Ca2+ stores. The unique gating of ICRAC has made it a favourite target of investigation for new signal transduction mechanisms; however, without molecular identification of the channel protein, such studies have been inconclusive. Here we show that the protein CaT1 (ref. 4), which has six membrane-spanning domains, exhibits the unique biophysical properties of ICRAC when expressed in mammalian cells. Like ICRAC, expressed CaT1 protein is Ca2+ selective, activated by a reduction in intracellular Ca2+ concentration, and inactivated by higher intracellular concentrations of Ca2+. The channel is indistinguishable from ICRAC in the following features: sequence of selectivity to divalent cations; an anomalous mole fraction effect; whole-cell current kinetics; block by lanthanum; loss of selectivity in the absence of divalent cations; and single-channel conductance to Na+ in divalent-ion-free conditions. CaT1 is activated by both passive and active depletion of calcium stores. We propose that CaT1 comprises all or part of the ICRAC pore.

MeSH terms

  • Animals
  • CHO Cells
  • Calcium / metabolism*
  • Calcium Channels / genetics
  • Calcium Channels / metabolism*
  • Cricetinae
  • Cricetulus
  • Electrophysiology
  • Rats
  • TRPV Cation Channels
  • Transfection
  • Tumor Cells, Cultured


  • Calcium Channels
  • TRPV Cation Channels
  • TRPV6 channel
  • Calcium