Functional analysis of CFTR chloride channel activity in cells with elevated MDR1 expression

2003 ◽  
Vol 304 (2) ◽  
pp. 248-252 ◽  
Author(s):  
Lishuang Cao ◽  
Grzegorz Owsianik ◽  
Martine Jaspers ◽  
Annelies Janssens ◽  
Harry Cuppens ◽  
...  
Keyword(s):  
Functional Analysis ◽  
Chloride Channel ◽  
Channel Activity ◽  
Mdr1 Expression ◽  
In Cells

scholarly journals The structural basis of lipid scrambling and inactivation in the endoplasmic reticulum scramblase TMEM16K

2018 ◽  
Author(s):  
Simon R. Bushell ◽  
Ashley C.W. Pike ◽  
Maria E. Falzone ◽  
Nils J. G. Rorsman ◽  
Chau M Ta ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Endoplasmic Reticulum ◽  
Conformational Changes ◽  
Chloride Channel ◽  
Autosomal Recessive ◽  
Structural Basis ◽  
Spinocerebellar Ataxia Type ◽  
Channel Activity ◽  
Dynamics Simulations ◽  
In Cells

AbstractMembranes in cells have defined distributions of lipids in each leaflet, controlled by lipid scramblases and flip/floppases. However, for some intracellular membranes such as the endoplasmic reticulum the scramblases have not been identified. Members of the TMEM16 family have either lipid scramblase and ion channel activity, or specific chloride channel activity. Although TMEM16K is widely distributed and associated with the neurological disorder autosomal recessive spinocerebellar ataxia type 10 (SCAR10), its location in cells, function and structure are largely uncharacterised. Here we show that TMEM16K is an ER-resident calcium-regulated lipid scramblase. Our crystal structures of TMEM16K show a scramblase fold, with an open lipid transporting groove. Additional structures solved by cryo-EM reveal extensive conformational changes extending from the cytoplasmic to the ER side of the membrane, giving a state with a closed lipid permeation pathway. Molecular dynamics simulations showed that the open-groove conformation is necessary for scramblase activity. Our results suggest mechanisms by which missense variants of TMEM16K could cause SCAR10 ataxia, providing new hypotheses to explore for therapy.

Сloning and Functional Analysis of SaCLCc1, a Gene Belonging to Chloride Channel Family (CLC) from the Halophyte Suaeda altissima (L.) Pall

2018 ◽  
Vol 481 (1) ◽  
pp. 104-107
Author(s):  
Yurii Balnokin ◽  
◽  
Igor Karpichev ◽  
Olga Mayorova ◽  
Olga Nedelyaeva ◽  
...  
Keyword(s):  
Functional Analysis ◽  
Chloride Channel ◽  
Suaeda Altissima

scholarly journals Arrhythmia and sudden death associated with elevated cardiac chloride channel activity

2011 ◽  
Vol 15 (11) ◽  
pp. 2307-2316 ◽  
Author(s):  
L. Ye ◽  
W. Zhu ◽  
P. H. Backx ◽  
M. A. Cortez ◽  
J. Wu ◽  
...  
Keyword(s):  
Sudden Death ◽  
Chloride Channel ◽  
Channel Activity

scholarly journals Endophilin A2 regulates calcium-activated chloride channel activity via selective autophagy-mediated TMEM16A degradation

2019 ◽  
Vol 41 (2) ◽  
pp. 208-217 ◽  
Author(s):  
Can-zhao Liu ◽  
Fei-ya Li ◽  
Xiao-fei Lv ◽  
Ming-ming Ma ◽  
Xiang-yu Li ◽  
...  
Keyword(s):  
Chloride Channel ◽  
Channel Activity ◽  
Selective Autophagy

Coexpression of complementary fragments of ClC-5 and restoration of chloride channel function in a Dent's disease mutation

2004 ◽  
Vol 286 (1) ◽  
pp. C79-C89 ◽  
Author(s):  
L. Mo ◽  
W. Xiong ◽  
T. Qian ◽  
H. Sun ◽  
N. K. Wills
Keyword(s):  
Chloride Channel ◽  
Functional Activity ◽  
Terminal Region ◽  
Channel Activity ◽  
Loss Of Function ◽  
C Protein ◽  
Dent’S Disease ◽  
Protein Fragments ◽  
Disease Mutation ◽  
Dent's Disease

The human hereditary disorder Dent's disease is linked to loss-of-function mutations of the chloride channel ClC-5. Many of these mutations involve insertion of premature stop codons, resulting in truncation of the protein. We determined whether the functional activity of ClC-5 could be restored by coexpression of the truncated protein (containing the NH2-terminal region) with its complementary “missing” COOH-terminal region. Split channel constructs for ClC-5, consisting of complementary N and C protein regions, were created at an arbitrary site in the COOH-terminal region (V655) and at four Dent's disease mutation sites (R347, Y617, R648, and R704). Coexpression of complementary fragments for the split channel at V655 produced currents with anion and pH sensitivity similar to those of wild-type ClC-5. Channel activity was similarly restored when complementary split channel constructs made for Dent's mutation R648 were coexpressed, but no ClC-5 currents were found when split channels for mutations R347, Y617, or R704 were coexpressed. Immunoblot and immunofluorescence studies of COS-7 cells revealed that N or C protein fragments could be transiently expressed and detected in the plasma membrane, even in split channels that failed to show functional activity. The results suggest that ClC-5 channel activity can be restored for specific Dent's mutations by expression of the missing portion of the ClC-5 molecule.

Epithelial Ca2+ channels sensitive to dihydropyridines and activated by hyperpolarizing voltages

1994 ◽  
Vol 267 (1) ◽  
pp. C157-C165 ◽  
Author(s):  
H. Matsunaga ◽  
B. A. Stanton ◽  
F. A. Gesek ◽  
P. A. Friedman
Keyword(s):  
Open Channel ◽  
Single Channel ◽  
Apical Membrane ◽  
Channel Activity ◽  
Channel Conductance ◽  
Single Channel Conductance ◽  
Nephron Segments ◽  
Convoluted Tubules ◽  
Ca2 Channels ◽  
In Cells

Parathyroid hormone (PTH) increases transcellular Ca2+ absorption in renal cortical thick ascending limbs and distal convoluted tubules (DCT). In cells isolated from these nephron segments, PTH increases Ca2+ uptake by a pathway that is sensitive to dihydropyridine-type agonists and antagonists (B. J. Bacskai and P. A. Friedman. Nature Lond. 347: 388-391, 1990). Patch-clamp techniques were used to identify Ca(2+)-permeable channels in DCT cells. Channel activity was detectable in cell-attached patches only in cells pretreated with PTH. Ca2+ channels exhibited prolonged open times (seconds), had a low single-channel conductance (2.1 pS), and open channel probability increased at hyperpolarizing voltages (-50 to -90 mV). Channel activity was sensitive to dihydropyridine-type compounds, nifedipine, and BAY K8644, as was Ca2+ uptake. However, Ca2+ entry was insensitive to verapamil or omega-conotoxin. These results demonstrate that these channels mediate PTH-stimulated apical membrane Ca2+ entry in DCT cells, which are the principal Ca(2+)-transporting cells of the kidney.

Cytosolic magnesium modulates calcium channel activity in mammalian ventricular cells

1989 ◽  
Vol 256 (2) ◽  
pp. C452-C455 ◽  
Author(s):  
Z. S. Agus ◽  
E. Kelepouris ◽  
I. Dukes ◽  
M. Morad
Keyword(s):  
Action Potential ◽  
Calcium Channel ◽  
Action Potential Duration ◽  
Calcium Current ◽  
Concentration Addition ◽  
High Threshold ◽  
Channel Activity ◽  
Mean Values ◽  
Ventricular Cells ◽  
In Cells

The effect of cytosolic free Mg2+ concentration on the regulation of myocardial function was studied by dialyzing isolated guinea pig ventricular myocytes with different internal Mg2+ concentrations [( Mg2+]i). We found that elevation of [Mg2+]i shortened the action potential and suppressed the Ca2+ current. Mean values recorded for action potential duration in cells dialyzed with solutions containing 0, 1.3, and 9.4 mM Mg2+ were 620 +/- 40, 400 +/- 25, and 60 +/- 10, respectively. The suppressive effect of [Mg2+]i on the action potential duration correlated significantly with the suppressive effects of [Mg2+]i on the Ca2+ current. In cells dialyzed with nominally zero Mg2+, calcium current was prominent (3.5 +/- 0.58 nA). At [Mg2+]i of 1.4 mM, calcium current was significantly smaller than in zero [Mg2+]i and was almost completely inhibited by dialysis of the cell with 9.4 mM Mg2+. The Mg2+-induced block of the Ca2+ current was due to steady-state inactivation of the high threshold calcium channel. The block was observed in the presence or absence of adenosine 3',5'-cylic monophosphate and was not reversed by elevation of external Ca2+ concentration, addition of adrenaline, or large negative potentials. These data suggest that cytosolic Mg2+ regulates Ca2+ channel activity by a novel mechanism, unrelated to its effect as a blocking particle of the open channel.

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