Is the gap junction channel -the connexon- made of connexin or ductin?

1993 ◽  
Vol 106 (2) ◽  
pp. 463-472 ◽  
Author(s):  
Malcolm E. Finbow ◽  
John D. Pitts
Keyword(s):  
Gap Junction ◽  
Gap Junction Channel

scholarly journals Cholesterol modulates function of connexin 43 gap junction channel via PKC pathway in H9c2 cells

2014 ◽  
Vol 1838 (8) ◽  
pp. 2019-2025 ◽  
Author(s):  
Jun Zou ◽  
Xiao-Yang Yue ◽  
Sheng-Chao Zheng ◽  
Guangwei Zhang ◽  
He Chang ◽  
...  
Keyword(s):  
Gap Junction ◽  
Connexin 43 ◽  
H9c2 Cells ◽  
Gap Junction Channel

A Closed Gap Junction Channel State Caused By A Single Site Mutation in the 3rd Transmembrane Helix

2004 ◽  
Vol 10 (S02) ◽  
pp. 1498-1499 ◽  
Author(s):  
Derek L Beahm ◽  
Guido Gaietta ◽  
Anjana Chandrasekhar ◽  
Galen M Hand ◽  
Amy Smock ◽  
...  
Keyword(s):  
Gap Junction ◽  
Transmembrane Helix ◽  
Single Site ◽  
Site Mutation ◽  
Channel State ◽  
Gap Junction Channel

Extended abstract of a paper presented at Microscopy and Microanalysis 2004 in Savannah, Georgia, USA, August 1–5, 2004.

scholarly journals Identification of amino acid residues lining the pore of a gap junction channel

2002 ◽  
Vol 159 (2) ◽  
pp. 349-360 ◽  
Author(s):  
I.M. Skerrett ◽  
J. Aronowitz ◽  
J.H. Shin ◽  
G. Cymes ◽  
E. Kasperek ◽  
...  
Keyword(s):  
Gap Junction ◽  
Molecular Level ◽  
Close Association ◽  
Pore Wall ◽  
Van Der Waals Interactions ◽  
Amino Acid Residues ◽  
Fixed Charges ◽  
Gap Junction Channel ◽  
Multicellular Organisms ◽  
Pore Lining

Gap junctions represent a ubiquitous and integral part of multicellular organisms, providing the only conduit for direct exchange of nutrients, messengers and ions between neighboring cells. However, at the molecular level we have limited knowledge of their endogenous permeants and selectivity features. By probing the accessibility of systematically substituted cysteine residues to thiol blockers (a technique called SCAM), we have identified the pore-lining residues of a gap junction channel composed of Cx32. Analysis of 45 sites in perfused Xenopus oocyte pairs defined M3 as the major pore-lining helix, with M2 (open state) or M1 (closed state) also contributing to the wider cytoplasmic opening of the channel. Additional mapping of a close association between M3 and M4 allowed the helices of the low resolution map (Unger et al., 1999. Science. 283:1176–1180) to be tentatively assigned to the connexin transmembrane domains. Contrary to previous conceptions of the gap junction channel, the residues lining the pore are largely hydrophobic. This indicates that the selective permeabilities of this unique channel class may result from novel mechanisms, including complex van der Waals interactions of permeants with the pore wall, rather than mechanisms involving fixed charges or chelation chemistry as reported for other ion channels.

Innexin-3 forms connexin-like intercellular channels

1999 ◽  
Vol 112 (14) ◽  
pp. 2391-2396 ◽  
Author(s):  
Y. Landesman ◽  
T.W. White ◽  
T.A. Starich ◽  
J.E. Shaw ◽  
D.A. Goodenough ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Gap Junction ◽  
Functional Properties ◽  
Xenopus Oocytes ◽  
Family Members ◽  
Electrical Coupling ◽  
Large Family ◽  
Gap Junction Channel ◽  
Intercellular Channels

Innexins comprise a large family of genes that are believed to encode invertebrate gap junction channel-forming proteins. However, only two Drosophila innexins have been directly tested for the ability to form intercellular channels and only one of those was active. Here we tested the ability of Caenorhabditis elegans family members INX-3 and EAT-5 to form intercellular channels between paired Xenopus oocytes. We show that expression of INX-3 but not EAT-5, induces electrical coupling between the oocyte pairs. In addition, analysis of INX-3 voltage and pH gating reveals a striking degree of conservation in the functional properties of connexin and innnexin channels. These data strongly support the idea that innexin genes encode intercellular channels.

Neuroprotection in the treatment of glaucoma – A focus on connexin43 gap junction channel blockers

2015 ◽  
Vol 95 ◽  
pp. 182-193 ◽  
Author(s):  
Ying-Shan Chen ◽  
Colin R. Green ◽  
Helen V. Danesh-Meyer ◽  
Ilva D. Rupenthal
Keyword(s):  
Gap Junction ◽  
Channel Blockers ◽  
Gap Junction Channel

Distinctive gap junction channel types connect WB cells, a clonal cell line derived from rat liver

1991 ◽  
Vol 260 (3) ◽  
pp. C513-C527 ◽  
Author(s):  
D. C. Spray ◽  
M. Chanson ◽  
A. P. Moreno ◽  
R. Dermietzel ◽  
P. Meda
Keyword(s):  
Gap Junction ◽  
Cell Line ◽  
Rat Liver ◽  
Connexin 43 ◽  
Single Channel ◽  
Freeze Fracture ◽  
Particle Sizes ◽  
Frequency Distributions ◽  
Gap Junction Channel ◽  
Junctional Conductance

Gap junctions, dye coupling, and junctional conductance were studied in a cell line (WB) that is derived from rat liver and displays a phenotype similar to “oval” cells. In freeze-fracture replicas, two distinctive particle sizes were detected in gap junctional plaques. Immunocytochemical studies indicated punctate staining at membrane appositions using antibodies to connexin 43 and to a brain gap junction-associated antigen (34 kDa). No staining was observed using antibodies prepared against rat liver gap junction proteins (connexins 32 and 26). Pairs of WB cells were electrically and dye coupled. Junctional conductance (gj) between cell pairs averaged approximately 10 nS; occasionally, gj was low enough that unitary junctional conductances (gamma j) could be detected. Using a CsCl-containing electrode solution, distinctive gamma j values were recorded: approximately 20-30 pS, approximately 80-90 pS, and the sum of the other sizes. The largest gamma j events were apparently due to random coincident openings or closures of the smaller channels. Several treatments reduced gj. Frequency distributions of gamma j were unaltered by 2 mM halothane or 3.5 heptanol, but the sizes of intermediate and largest events were reduced slightly by 100 nM phorbol ester, and the relative frequency of the largest events was increased by 10 microM glutaraldehyde. We conclude that the distinctive gamma j values represent openings and closures of two distinct types of gap junction channels rather than substates of a single channel type; these unitary conductances may correspond to the dual immunoreactivity and to the two particle sizes seen in freeze fracture.

scholarly journals Zinc Modulation of Hemi-Gap-Junction Channel Currents in Retinal Horizontal Cells

2009 ◽  
Vol 101 (4) ◽  
pp. 1774-1780 ◽  
Author(s):  
Ziyi Sun ◽  
Dao-Qi Zhang ◽  
Douglas G. McMahon
Keyword(s):  
Gap Junction ◽  
Inhibitory Action ◽  
Divalent Cations ◽  
Horizontal Cells ◽  
Visual Signals ◽  
Histidine Residues ◽  
Gap Junction Channel ◽  
And Function ◽  
Channel Currents

Hemi-gap-junction (HGJ) channels of retinal horizontal cells (HCs) function as transmembrane ion channels that are modulated by voltage and calcium. As an endogenous retinal neuromodulator, zinc, which is coreleased with glutamate at photoreceptor synapses, plays an important role in shaping visual signals by acting on postsynaptic HCs in vivo. To understand more fully the regulation and function of HC HGJ channels, we examined the effect of Zn2+ on HGJ channel currents in bass retinal HCs. Hemichannel currents elicited by depolarization in Ca2+-free medium and in 1 mM Ca2+ medium were significantly inhibited by extracellular Zn2+. The inhibition by Zn2+ of hemichannel currents was dose dependent with a half-maximum inhibitory concentration of 37 μM. Compared with other divalent cations, Zn2+ exhibited higher inhibitory potency, with the order being Zn2+ > Cd2+ ≈ Co2+ > Ca2+ > Ba2+ > Mg2+. Zn2+ and Ca2+ were found to modulate HGJ channels independently in additivity experiments. Modification of histidine residues with N-bromosuccinimide suppressed the inhibitory action of Zn2+, whereas modification of cysteine residues had no significant effect on Zn2+ inhibition. Taken together, these results suggest that zinc acts on HGJ channels in a calcium-independent way and that histidine residues on the extracellular domain of HGJ channels mediate the inhibitory action of zinc.

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