scholarly journals Mono-Heteromeric Configurations of Gap Junction Channels Formed by Connexin43 and Connexin45 Reduce Unitary Conductance and Determine both Voltage Gating and Metabolic Flux Asymmetry

2017 ◽  
Vol 8 ◽  
Author(s):  
Guoqiang Zhong ◽  
Nazem Akoum ◽  
Daniel A. Appadurai ◽  
Volodya Hayrapetyan ◽  
Osman Ahmed ◽  
...  
Keyword(s):  
Gap Junction ◽  
Metabolic Flux ◽  
Voltage Gating ◽  
Gap Junction Channels ◽  
Unitary Conductance

scholarly journals Stochastic 16-State Model of Voltage Gating of Gap-Junction Channels Enclosing Fast and Slow Gates

2012 ◽  
Vol 102 (11) ◽  
pp. 2471-2480 ◽  
Author(s):  
Nerijus Paulauskas ◽  
Henrikas Pranevicius ◽  
Jonas Mockus ◽  
Feliksas F. Bukauskas
Keyword(s):  
Gap Junction ◽  
Voltage Gating ◽  
State Model ◽  
Gap Junction Channels

scholarly journals A Stochastic Model of Voltage-Gating of Connexin-Based Gap Junction Channels Containing Fast and Slow Gates

2011 ◽  
Vol 100 (3) ◽  
pp. 564a
Author(s):  
Nerijus Paulauskas ◽  
Henrikas Pranevicius ◽  
Feliksas Bukauskas
Keyword(s):  
Stochastic Model ◽  
Gap Junction ◽  
Voltage Gating ◽  
Gap Junction Channels

Continuous Time Markov Chain Models of Voltage Gating of Gap Junction Channels

2014 ◽  
Vol 43 (2) ◽  
Author(s):  
H. Pranevicius ◽  
M. Pranevicius ◽  
O. Pranevicius ◽  
M. Snipas ◽  
N. Paulauskas ◽  
...  
Keyword(s):  
Markov Chain ◽  
Gap Junction ◽  
Continuous Time ◽  
Voltage Gating ◽  
Continuous Time Markov Chain ◽  
Gap Junction Channels ◽  
Markov Chain Models

scholarly journals The Carboxyl Terminal Domain Regulates the Unitary Conductance and Voltage Dependence of Connexin40 Gap Junction Channels

2001 ◽  
Vol 88 (7) ◽  
pp. 666-673 ◽  
Author(s):  
Justus M. B. Anumonwo ◽  
Steven M. Taffet ◽  
Hong Gu ◽  
Marc Chanson ◽  
Alonso P. Moreno ◽  
...  
Keyword(s):  
Gap Junction ◽  
Voltage Dependence ◽  
Gap Junction Channels ◽  
Terminal Domain ◽  
Unitary Conductance ◽  
Carboxyl Terminal Domain ◽  
Carboxyl Terminal

Properties of gap junction channels formed of connexin 45 endogenously expressed in human hepatoma (SKHep1) cells

1995 ◽  
Vol 268 (2) ◽  
pp. C356-C365 ◽  
Author(s):  
A. P. Moreno ◽  
J. G. Laing ◽  
E. C. Beyer ◽  
D. C. Spray
Keyword(s):  
Gap Junction ◽  
Voltage Dependence ◽  
Hepatoma Cell ◽  
Hepatoma Cell Line ◽  
Voltage Sensitivity ◽  
Gap Junction Channels ◽  
Unitary Conductance ◽  
Junction Protein ◽  
Voltage Dependent ◽  
Gap Junctional

We have evaluated the voltage dependence and unitary conductance of gap junctional channels that were recorded in a clone isolated from the hepatoma cell line SKHep1. In this clonal population (designated SKHep1A), Northern blots, immunoprecipitation, and immunohistochemical staining demonstrated the expression of connexin (Cx) 45; no other gap junction protein was identified by these techniques, although weak hybridization with Cx40 was detected. Macroscopic junctional conductance (gj) in these cells was low, averaging 1.3 nS, and was steeply voltage dependent. Parameters of voltage sensitivity were as follows: voltage at which voltage-sensitive conductance is reduced by 50%, 13.4 mV; steepness of relation, 0.115 (corresponding to 2.7 gating charges), and voltage-insensitive fraction of residual to total conductance approximately 0.06. Unitary conductance (gamma j) of these junctional channels averaged 32 +/- 8 pS; although gamma j was independent of transjunctional voltage (Vj), at high Vj values (> 50 mV), smaller conductance values were also detected. Open probabilities of the 30-pS channels at various Vj values closely matched the predicted voltage-dependent component of macroscopic gj, the residual conductance at high Vj might be attributable to the smaller conductance events. The voltage dependence of human Cx45 gap junction channels is as steep as that seen for channels formed by Xenopus Cx38 and is much steeper than that previously reported for channels formed of the highly homologous chick Cx45 and for other mammalian connexins expressed either endogenously or exogenously.

Biophysical characterization of zebrafish connexin35 hemichannels

2004 ◽  
Vol 287 (6) ◽  
pp. C1596-C1604 ◽  
Author(s):  
Virginijus Valiunas ◽  
Rickie Mui ◽  
Elizabeth McLachlan ◽  
Gunnar Valdimarsson ◽  
Peter R. Brink ◽  
...  
Keyword(s):  
Gap Junction ◽  
Single Channel ◽  
Biophysical Characterization ◽  
Whole Cell ◽  
Gap Junction Channels ◽  
N2a Cells ◽  
Unitary Conductance ◽  
Cell Depolarization

A subset of connexins can form unopposed hemichannels in expression systems, providing an opportunity for comparison of hemichannel gating properties with those of intact gap junction channels. Zebrafish connexin35 (Cx35) is a member of the Cx35/Cx36 subgroup of connexins highly expressed in the retina and brain. In the present study, we have shown that Cx35 expression in Xenopus oocytes and N2A cells produced large outward whole cell currents on cell depolarization. Using whole cell, cell-attached, and excised patch configurations, we obtained multichannel and single-channel current recordings attributable to the Cx35 hemichannels ( Ihc) that were activated and increased by stepwise depolarization of membrane potential ( Vm) and deactivated by hyperpolarization. The currents were not detected in untransfected N2A cells or in control oocytes injected with antisense Cx38. However, water-injected oocytes that were not treated with antisense showed activities attributable to Cx38 hemichannels that were easily distinguishable from Cx35 hemichannels by a significantly larger unitary conductance ( γhc: 250–320 pS). The γhc of Cx35 hemichannels exhibited a pronounced Vm dependence; i.e., γhc increased/decreased with relative hyperpolarization/depolarization ( γhc was 72 pS at Vm = −100 mV and 35 pS at Vm = 100 mV). Extrapolation to Vm = 0 mV predicted a γhc of 48 pS, suggesting a unitary conductance of intact Cx35 gap junction channels of ∼24 pS. Channel gating was also Vm dependent: open time declined with negative Vm and increased with positive Vm. The ability to break down the complex gating of intact intercellular channels into component hemichannels in vitro will help to evaluate putative physiological roles for hemichannels in vivo.

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