Voltage dependence of the Ca2+-activated cation channel TRPM4.
Article Details
- CitationCopy to clipboard
Nilius B, Prenen J, Droogmans G, Voets T, Vennekens R, Freichel M, Wissenbach U, Flockerzi V
Voltage dependence of the Ca2+-activated cation channel TRPM4.
J Biol Chem. 2003 Aug 15;278(33):30813-20. Epub 2003 Jun 10.
- PubMed ID
- 12799367 [ View in PubMed]
- Abstract
TRPM4 is a Ca2+-activated but Ca2+-impermeable cation channel. An increase of [Ca2+]i induces activation and subsequent reduction of currents through TRPM4 channels. This inactivation is strikingly decreased in cell-free patches. In whole cell and cell-free configuration, currents through TRPM4 deactivate rapidly at negative potentials. At positive potentials, currents are much larger and activate slowly. This voltage-dependent behavior induces a striking outward rectification of the steady state currents. The instantaneous current-voltage relationship, derived from the amplitude of tail currents following a prepulse to positive potentials, is linear. Currents show a Boltzmann type of activation; the fraction of open channels increases at positive potentials and is low at negative potentials. Voltage dependence is not due to block by divalent cations or to voltage-dependent binding of intracellular Ca2+ to an activator site, indicating that TRPM4 is a transient receptor potential channel with an intrinsic voltage-sensing mechanism. Voltage dependence of TRPM4 may be functionally important, especially in excitable tissues generating plateau-like or bursting action potentials.