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

A. P. Moreno, J. G. Laing, E. C. Beyer, David C. Spray

Research output: Contribution to journalArticle

122 Citations (Scopus)

Abstract

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 (g(j)) 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 ≃ 0.06. Unitary conductance (γ(j)) of these junctional channels averaged 32 ± 8 pS; although γ(j) was independent of transjunctional voltage (V(j)), at high V(j) values (>50 mV), smaller conductance values were also detected. Open probabilities of the 30-pS channels at various V(j) values closely matched the predicted voltage-dependent component of macroscopic g(j); the residual conductance at high V(j) 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.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Cell Physiology
Volume268
Issue number2 37-2
StatePublished - 1995
Externally publishedYes

Fingerprint

connexins
Connexins
gap junctions
Gap Junctions
hepatoma
Hepatocellular Carcinoma
Electric potential
Xenopus
Immunoprecipitation
Northern Blotting
Clone Cells
cells
Staining and Labeling
Cell Line
Northern blotting
hybridization
chicks
cell lines
clones
Population

ASJC Scopus subject areas

  • Clinical Biochemistry
  • Cell Biology
  • Physiology
  • Agricultural and Biological Sciences(all)

Cite this

Properties of gap junction channels formed of connexin 45 endogenously expressed in human hepatoma (SKHep1) cells. / Moreno, A. P.; Laing, J. G.; Beyer, E. C.; Spray, David C.

In: American Journal of Physiology - Cell Physiology, Vol. 268, No. 2 37-2, 1995.

Research output: Contribution to journalArticle

@article{e7ffd778d1f24166b94ee2e835ecd2c9,
title = "Properties of gap junction channels formed of connexin 45 endogenously expressed in human hepatoma (SKHep1) cells",
abstract = "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 (g(j)) 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 ≃ 0.06. Unitary conductance (γ(j)) of these junctional channels averaged 32 ± 8 pS; although γ(j) was independent of transjunctional voltage (V(j)), at high V(j) values (>50 mV), smaller conductance values were also detected. Open probabilities of the 30-pS channels at various V(j) values closely matched the predicted voltage-dependent component of macroscopic g(j); the residual conductance at high V(j) 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.",
author = "Moreno, {A. P.} and Laing, {J. G.} and Beyer, {E. C.} and Spray, {David C.}",
year = "1995",
language = "English (US)",
volume = "268",
journal = "American Journal of Physiology - Renal Fluid and Electrolyte Physiology",
issn = "1931-857X",
publisher = "American Physiological Society",
number = "2 37-2",

}

TY - JOUR

T1 - Properties of gap junction channels formed of connexin 45 endogenously expressed in human hepatoma (SKHep1) cells

AU - Moreno, A. P.

AU - Laing, J. G.

AU - Beyer, E. C.

AU - Spray, David C.

PY - 1995

Y1 - 1995

N2 - 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 (g(j)) 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 ≃ 0.06. Unitary conductance (γ(j)) of these junctional channels averaged 32 ± 8 pS; although γ(j) was independent of transjunctional voltage (V(j)), at high V(j) values (>50 mV), smaller conductance values were also detected. Open probabilities of the 30-pS channels at various V(j) values closely matched the predicted voltage-dependent component of macroscopic g(j); the residual conductance at high V(j) 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.

AB - 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 (g(j)) 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 ≃ 0.06. Unitary conductance (γ(j)) of these junctional channels averaged 32 ± 8 pS; although γ(j) was independent of transjunctional voltage (V(j)), at high V(j) values (>50 mV), smaller conductance values were also detected. Open probabilities of the 30-pS channels at various V(j) values closely matched the predicted voltage-dependent component of macroscopic g(j); the residual conductance at high V(j) 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.

UR - http://www.scopus.com/inward/record.url?scp=0028900935&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0028900935&partnerID=8YFLogxK

M3 - Article

C2 - 7532358

AN - SCOPUS:0028900935

VL - 268

JO - American Journal of Physiology - Renal Fluid and Electrolyte Physiology

JF - American Journal of Physiology - Renal Fluid and Electrolyte Physiology

SN - 1931-857X

IS - 2 37-2

ER -