Rapid gating and anion permeability of an intracellular aquaporin

Nature ◽  
10.1038/46045 ◽  
1999 ◽  
Vol 402 (6758) ◽  
pp. 184-187 ◽  
Author(s):  
Masato Yasui ◽  
Akihiro Hazama ◽  
Tae-Hwan Kwon ◽  
Søren Nielsen ◽  
Wm. B. Guggino ◽  
...  
Keyword(s):  
Anion Permeability

scholarly journals Calcium-calmodulin does not alter the anion permeability of the mouse TMEM16A calcium-activated chloride channel

2014 ◽  
Vol 144 (1) ◽  
pp. 115-124 ◽  
Author(s):  
Yawei Yu ◽  
Ai-Seon Kuan ◽  
Tsung-Yu Chen
Keyword(s):  
Series Resistance ◽  
Transmembrane Protein ◽  
Reversal Potential ◽  
Binding Motifs ◽  
Channel Pore ◽  
Ionic Potential ◽  
Anion Permeability ◽  
Anion Permeation ◽  
Gated Channel ◽  
Whole Cell Recordings

The transmembrane protein TMEM16A forms a Ca2+-activated Cl− channel that is permeable to many anions, including SCN−, I−, Br−, Cl−, and HCO3−, and has been implicated in various physiological functions. Indeed, controlling anion permeation through the TMEM16A channel pore may be critical in regulating the pH of exocrine fluids such as the pancreatic juice. The anion permeability of the TMEM16A channel pore has recently been reported to be modulated by Ca2+-calmodulin (CaCaM), such that the pore of the CaCaM-bound channel shows a reduced ability to discriminate between anions as measured by a shift of the reversal potential under bi-ionic conditions. Here, using a mouse TMEM16A clone that contains the two previously identified putative CaM-binding motifs, we were unable to demonstrate such CaCaM-dependent changes in the bi-ionic potential. We confirmed the activity of CaCaM used in our study by showing CaCaM modulation of the olfactory cyclic nucleotide–gated channel. We suspect that the different bi-ionic potentials that were obtained previously from whole-cell recordings in low and high intracellular [Ca2+] may result from different degrees of bi-ionic potential shift secondary to a series resistance problem, an ion accumulation effect, or both.

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