Small-conductance chloride channels induced by cAMP, Ca2+, and hypotonicity in HT29 cells: ion selectivity, additivity and stilbene sensitivity

1992 ◽  
Vol 421 (5) ◽  
pp. 447-454 ◽  
Author(s):  
R. Kubitz ◽  
R. Warth ◽  
N. Allert ◽  
K. Kunzelmann ◽  
R. Greger
Keyword(s):  
Chloride Channels ◽  
Ion Selectivity ◽  
Ht29 Cells ◽  
Small Conductance

scholarly journals Dynamic change of electrostatic field in TMEM16F permeation pathway shifts its ion selectivity

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Wenlei Ye ◽  
Tina W Han ◽  
Mu He ◽  
Yuh Nung Jan ◽  
Lily Yeh Jan
Keyword(s):  
Ion Channel ◽  
Electrostatic Field ◽  
Chloride Channels ◽  
Ion Selectivity ◽  
Dynamic Change ◽  
Ion Permeability ◽  
Permeability Ratio ◽  
Phospholipid Scramblase ◽  
A Charge ◽  
Small Conductance

TMEM16F is activated by elevated intracellular Ca2+, and functions as a small-conductance ion channel and as a phospholipid scramblase. In contrast to its paralogs, the TMEM16A/B calcium-activated chloride channels, mouse TMEM16F has been reported as a cation-, anion-, or non-selective ion channel, without a definite conclusion. Starting with the Q559K mutant that shows no current rundown and less outward rectification in excised patch, we found that the channel shifted its ion selectivity in response to the change of intracellular Ca2+ concentration, with an increased permeability ratio of Cl- to Na+ (PCl-/PNa+) at a higher Ca2+ level. The gradual shift of relative ion permeability did not correlate with the channel activation state. Instead, it was indicative of an alteration of electrostatic field in the permeation pathway. The dynamic change of ion selectivity suggests a charge-screening mechanism for TMEM16F ion conduction, and it provides hints to further studies of TMEM16F physiological functions.

Chloride channels in apical membrane of primary cultures of rabbit distal bright convoluted tubule

1994 ◽  
Vol 266 (4) ◽  
pp. F543-F553 ◽  
Author(s):  
V. Poncet ◽  
M. Tauc ◽  
M. Bidet ◽  
P. Poujeol
Keyword(s):  
Chloride Channels ◽  
Apical Membrane ◽  
Primary Cultures ◽  
Transmembrane Conductance Regulator ◽  
Patch Clamp Technique ◽  
Cl Channel ◽  
Current Voltage ◽  
Cl Channels ◽  
Inside Out ◽  
Small Conductance

Using the patch clamp technique on the apical membrane of primary cultures of rabbit distal bright convoluted tubule cells (DCTb), two types of Cl- channel were identified. A small channel of 9 pS was observed in 9% of the patches. Cells pretreated with 1 mM 8-bromoadenosine 3',5'-cyclic monophosphate (8-BrcAMP) or 5 microM forskolin increased the expression of Cl- channels by 26 and 37%, respectively. In cell-attached and excised inside-out patches, the current-voltage (I-V) relationships of the 9-pS channel were linear. In only 1 out of 47 active patches was the small-conductance Cl- channel still active 1 h after membrane excision. The addition of 0.1 microM of the catalytic subunit protein kinase A with 2 mM ATP to the cytoplasmic side restored channel activity in 8 out of 15 excised membrane patches. In 5 out of 467 patches of stimulated or nonstimulated cells, a larger Cl- conductance of 30 pS was also recorded. In excised inside-out patches this channel outwardly rectified and was activated by strong depolarization. In cultured DCTb cells, the small-conductance, cAMP-activated Cl- channel shares many properties with the cystic fibrosis transmembrane conductance regulator. Our results suggest that at least the small-conductance channel may participate in Cl- secretion across the apical membrane of DCTb in primary culture. This secretion may increase the rate of the apical Cl-/HCO3- exchange indirectly by enhancing the inwardly-directed Cl- gradient.

scholarly journals Small conductance chloride channels in the apical membrane of thyroid cells

FEBS Letters ◽  
1990 ◽  
Vol 259 (2) ◽  
pp. 263-268 ◽  
Author(s):  
G. Champigny ◽  
B. Verrier ◽  
C. Gérard ◽  
J. Mauchamp ◽  
M. Lazdunski
Keyword(s):  
Chloride Channels ◽  
Apical Membrane ◽  
Thyroid Cells ◽  
Small Conductance

Small-conductance Cl? channels in HT29 cells: activation by Ca2+, hypotonic cell swelling and 8-Br-cGMP

1992 ◽  
Vol 421 (2-3) ◽  
pp. 238-246 ◽  
Author(s):  
K. Kunzelmann ◽  
R. Kubitz ◽  
M. Grolik ◽  
R. Warth ◽  
R. Greger
Keyword(s):  
Cell Swelling ◽  
Ht29 Cells ◽  
Cl Channels ◽  
Hypotonic Cell Swelling ◽  
Small Conductance

scholarly journals Cryo-EM structure of a proton-activated chloride channel TMEM206

2021 ◽  
Vol 7 (9) ◽  
pp. eabe5983
Author(s):  
Zengqin Deng ◽  
Yonghui Zhao ◽  
Jing Feng ◽  
Jingying Zhang ◽  
Haiyan Zhao ◽  
...  
Keyword(s):  
Chloride Channel ◽  
Chloride Channels ◽  
Ion Selectivity ◽  
Chloride Ion ◽  
Transmembrane Segments ◽  
New Class ◽  
The Core ◽  
Cryo Electron Microscopy ◽  
Extracellular Region ◽  
Evolutionarily Conserved

TMEM206 has been recently identified as an evolutionarily conserved chloride channel that underlies ubiquitously expressed, proton-activated, outwardly rectifying anion currents. Here, we report the cryo–electron microscopy structure of pufferfish TMEM206, which forms a trimeric channel, with each subunit comprising two transmembrane segments and a large extracellular domain. An ample vestibule in the extracellular region is accessible laterally from the three side portals. The central pore contains multiple constrictions. A conserved lysine residue near the cytoplasmic end of the inner helix forms the presumed chloride ion selectivity filter. Unprecedentedly, the core structure and assembly closely resemble those of the epithelial sodium channel/degenerin family of sodium channels that are unrelated in amino acid sequence and conduct cations instead of anions. Together with electrophysiology, this work provides insights into ion conduction and gating for a new class of chloride channels that is architecturally distinct from previously characterized chloride channel families.

scholarly journals Cryo-EM structure of a proton-activated chloride channel TMEM206

2020 ◽  
Author(s):  
Zengqin Deng ◽  
Yonghui Zhao ◽  
Jing Feng ◽  
Jingying Zhang ◽  
Haiyan Zhao ◽  
...  
Keyword(s):  
Chloride Channel ◽  
Chloride Channels ◽  
Ion Selectivity ◽  
Chloride Ion ◽  
Ion Conduction ◽  
Transmembrane Segments ◽  
New Class ◽  
Cryo Electron Microscopy ◽  
Extracellular Region ◽  
Evolutionarily Conserved

AbstractTMEM206 has been recently identified as an evolutionarily conserved chloride channel that underlies ubiquitously expressed, proton-activated, outwardly rectifying anion currents. Here we report the cryo-electron microscopy structure of pufferfish TMEM206, which forms a trimeric channel, with each subunit comprising two transmembrane segments, the outer and inner helices, and a large extracellular domain. An ample vestibule in the extracellular region is accessible laterally from the three side portals. The central pore contains multiple constrictions preventing ion conduction. A conserved lysine residue near the cytoplasmic end of the inner helix forms the presumed chloride ion selectivity filter. Unprecedentedly, the core structure and assembly closely resemble those of the epithelial sodium channel/degenerin family of sodium channels that are unrelated in amino acid sequence and conduct cations instead of anions. Together with electrophysiology, this work provides insights into ion conduction and gating for a new class of chloride channels that is architecturally distinct from previously characterized chloride channel families.

scholarly journals Subdued, a TMEM16 family Ca2+-activated Cl− channel in Drosophila melanogaster with an unexpected role in host defense

eLife ◽  
2013 ◽  
Vol 2 ◽  
Author(s):  
Xiu Ming Wong ◽  
Susan Younger ◽  
Christian J Peters ◽  
Yuh Nung Jan ◽  
Lily Y Jan
Keyword(s):  
Drosophila Melanogaster ◽  
Host Defense ◽  
Chloride Channels ◽  
Pathogenic Bacteria ◽  
Ion Selectivity ◽  
Kinetic Properties ◽  
Amino Acid Substitutions ◽  
Biophysical Properties ◽  
Evolutionarily Conserved ◽  
Open Question

TMEM16A and TMEM16B are calcium-activated chloride channels (CaCCs) with important functions in mammalian physiology. Whether distant relatives of the vertebrate TMEM16 families also form CaCCs is an intriguing open question. Here we report that a TMEM16 family member from Drosophila melanogaster, Subdued (CG16718), is a CaCC. Amino acid substitutions of Subdued alter the ion selectivity and kinetic properties of the CaCC channels heterologously expressed in HEK 293T cells. This Drosophila channel displays characteristics of classic CaCCs, thereby providing evidence for evolutionarily conserved biophysical properties in the TMEM16 family. Additionally, we show that knockout flies lacking subdued gene activity more readily succumb to death caused by ingesting the pathogenic bacteria Serratia marcescens, suggesting that subdued has novel functions in Drosophila host defense.

scholarly journals Dynamic Change of Electrostatic Field in TMEM16F Permeation Pathway Shifts Its Ion Selectivity

2019 ◽  
Author(s):  
Wenlei Ye ◽  
Tina W. Han ◽  
Mu He ◽  
Yuh Nung Jan ◽  
Lily Y. Jan
Keyword(s):  
Membrane Potential ◽  
Ion Channel ◽  
Electrostatic Field ◽  
Positive Feedback ◽  
Ion Selectivity ◽  
Dynamic Change ◽  
Divalent Ions ◽  
Phospholipid Scramblase ◽  
Intracellular Ca ◽  
Small Conductance

AbstractTMEM16F is activated by elevated intracellular Ca2+, and functions both as a small-conductance ion channel permeable to Ca2+ and as a phospholipid scramblase. It is important to hold this positive feedback in check to prevent prolonged Ca2+-overloading in cells. We hypothesize that TMEM16F shifts its ion selectivity so that it is more permeable to Cl− than cations at high intracellular Ca2+ concentration. We tested this hypothesis with the Q559K mutant that shows no current rundown in excised patch with prolonged Ca2+ elevation. Recorded in NaCl−based solution, the channel shifted its ion selectivity from Na+-selective to Cl−-selective when intracellular Ca2+ was increased. The ion selectivity switch did not correlate with changes of channel open state. Rather, it was indicative of an alteration of electrostatic field in the permeation pathway. Shifting ion-selectivity synergistically by intracellular divalent ions and membrane potential could work as a built-in mechanism that allows TMEM16F to brake the positive feedback.

Small and intermediate conductance chloride channels in HT29 cells

1993 ◽  
Vol 424 (5-6) ◽  
pp. 456-464 ◽  
Author(s):  
C. P. Hansen ◽  
B. Roch ◽  
K. Kunzelmann ◽  
R. Kubitz ◽  
R. Greger
Keyword(s):  
Chloride Channels ◽  
Ht29 Cells
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