Abstract
The Ca2+-permeable cation channel TRPA1 acts as an ionotropic receptor for various pungent compounds and as a noxious cold sensor in sensory neurons. It is unclear what proportion of the TRPA1-mediated current is carried by Ca2+ ions and how the permeation pathway changes during stimulation. Here, based on the relative permeability of the nonstimulated channel to cations of different size, we estimated a pore diameter of ∼11 Å. Combined patch-clamp and Fura-2 fluorescence recordings revealed that with 2 mM extracellular Ca2+, and at a membrane potential of -80 mV, ∼17% of the inward TRPA1 current is carried by Ca2+. Stimulation with mustard oil evoked an apparent dilatation of the pore of 3 Å and an increase in divalent cation selectivity and fractional Ca2+ current. Mutations in the putative pore that reduced the divalent permeability and fractional Ca2+ current also prevented mustard-oil-induced increases in Ca2+ permeation. It is interesting that fractional Ca2+ currents for wild-type and mutant TRPA1 were consistently higher than values predicted based on biionic reversal potentials using the Goldman-Hodgkin-Katz equation, suggesting that binding of Ca2+ in the pore hinders monovalent cation permeation. We conclude that the pore of TRPA1 is dynamic and supports a surprisingly large Ca2+ influx.
| Original language | English |
|---|---|
| Pages (from-to) | 773-783 |
| Number of pages | 11 |
| Journal | Biophysical Journal |
| Volume | 98 |
| Issue number | 5 |
| DOIs | |
| Publication status | Published - Mar 3 2010 |
| Externally published | Yes |
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All Science Journal Classification (ASJC) codes
- Biophysics
Cite this
Agonist-induced changes in Ca2+ permeation through the nociceptor cation channel TRPA1. / Karashima, Yuji; Prenen, Jean; Talavera, Karel; Janssens, Annelies; Voets, Thomas; Nilius, Bernd.
In: Biophysical Journal, Vol. 98, No. 5, 03.03.2010, p. 773-783.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Agonist-induced changes in Ca2+ permeation through the nociceptor cation channel TRPA1
AU - Karashima, Yuji
AU - Prenen, Jean
AU - Talavera, Karel
AU - Janssens, Annelies
AU - Voets, Thomas
AU - Nilius, Bernd
PY - 2010/3/3
Y1 - 2010/3/3
N2 - The Ca2+-permeable cation channel TRPA1 acts as an ionotropic receptor for various pungent compounds and as a noxious cold sensor in sensory neurons. It is unclear what proportion of the TRPA1-mediated current is carried by Ca2+ ions and how the permeation pathway changes during stimulation. Here, based on the relative permeability of the nonstimulated channel to cations of different size, we estimated a pore diameter of ∼11 Å. Combined patch-clamp and Fura-2 fluorescence recordings revealed that with 2 mM extracellular Ca2+, and at a membrane potential of -80 mV, ∼17% of the inward TRPA1 current is carried by Ca2+. Stimulation with mustard oil evoked an apparent dilatation of the pore of 3 Å and an increase in divalent cation selectivity and fractional Ca2+ current. Mutations in the putative pore that reduced the divalent permeability and fractional Ca2+ current also prevented mustard-oil-induced increases in Ca2+ permeation. It is interesting that fractional Ca2+ currents for wild-type and mutant TRPA1 were consistently higher than values predicted based on biionic reversal potentials using the Goldman-Hodgkin-Katz equation, suggesting that binding of Ca2+ in the pore hinders monovalent cation permeation. We conclude that the pore of TRPA1 is dynamic and supports a surprisingly large Ca2+ influx.
AB - The Ca2+-permeable cation channel TRPA1 acts as an ionotropic receptor for various pungent compounds and as a noxious cold sensor in sensory neurons. It is unclear what proportion of the TRPA1-mediated current is carried by Ca2+ ions and how the permeation pathway changes during stimulation. Here, based on the relative permeability of the nonstimulated channel to cations of different size, we estimated a pore diameter of ∼11 Å. Combined patch-clamp and Fura-2 fluorescence recordings revealed that with 2 mM extracellular Ca2+, and at a membrane potential of -80 mV, ∼17% of the inward TRPA1 current is carried by Ca2+. Stimulation with mustard oil evoked an apparent dilatation of the pore of 3 Å and an increase in divalent cation selectivity and fractional Ca2+ current. Mutations in the putative pore that reduced the divalent permeability and fractional Ca2+ current also prevented mustard-oil-induced increases in Ca2+ permeation. It is interesting that fractional Ca2+ currents for wild-type and mutant TRPA1 were consistently higher than values predicted based on biionic reversal potentials using the Goldman-Hodgkin-Katz equation, suggesting that binding of Ca2+ in the pore hinders monovalent cation permeation. We conclude that the pore of TRPA1 is dynamic and supports a surprisingly large Ca2+ influx.
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U2 - 10.1016/j.bpj.2009.11.007
DO - 10.1016/j.bpj.2009.11.007
M3 - Article
VL - 98
SP - 773
EP - 783
JO - Biophysical Journal
JF - Biophysical Journal
SN - 0006-3495
IS - 5
ER -