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Title: Mg2+-dependent gating and strong inward rectification of the cation channel TRPV6
Authors: Voets, Thomas ×
Janssens, Annelies
Prenen, Jean
Droogmans, Guy
Nilius, Bernd #
Issue Date: Mar-2003
Series Title: The Journal of general physiology vol:121 issue:3 pages:245-60
Abstract: TRPV6 (CaT1/ECaC2), a highly Ca(2+)-selective member of the TRP superfamily of cation channels, becomes permeable to monovalent cations in the absence of extracellular divalent cations. The monovalent currents display characteristic voltage-dependent gating and almost absolute inward rectification. Here, we show that these two features are dependent on the voltage-dependent block/unblock of the channel by intracellular Mg(2+). Mg(2+) blocks the channel by binding to a site within the transmembrane electrical field where it interacts with permeant cations. The block is relieved at positive potentials, indicating that under these conditions Mg(2+) is able to permeate the selectivity filter of the channel. Although sizeable outward monovalent currents were recorded in the absence of intracellular Mg(2+), outward conductance is still approximately 10 times lower than inward conductance under symmetric, divalent-free ionic conditions. This Mg(2+)-independent rectification was preserved in inside-out patches and not altered by high intracellular concentrations of spermine, indicating that TRPV6 displays intrinsic rectification. Neutralization of a single aspartate residue within the putative pore loop abolished the Mg(2+) sensitivity of the channel, yielding voltage-independent, moderately inwardly rectifying monovalent currents in the presence of intracellular Mg(2+). The effects of intracellular Mg(2+) on TRPV6 are partially reminiscent of the gating mechanism of inwardly rectifying K(+) channels and may represent a novel regulatory mechanism for TRPV6 function in vivo.
URI: 
ISSN: 0022-1295
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Physiology Section (-)
Department of Cellular and Molecular Medicine - miscellaneous
Laboratory of Ion Channel Research
× corresponding author
# (joint) last author

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