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The functional diversity of gap junction intercellular channels arising from the large number of connexin isoforms is significantly increased by heterotypic interactions between members of this family. This is particularly evident in the rectifying behavior of Cx26/Cx32 heterotypic channels (. Proc. Natl. Acad. Sci. USA. 88:8410-8414). The channel properties responsible for producing the rectifying current observed for Cx26/Cx32 heterotypic gap junction channels were determined in transfected mouse neuroblastoma 2A (N2A) cells. Transfectants revealed maximum unitary conductances (gamma(j)) of 135 pS for Cx26 and 53 pS for Cx32 homotypic channels in 120 mM KCl. Anionic substitution of glutamate for Cl indicated that Cx26 channels favored cations by 2.6:1, whereas Cx32 channels were relatively nonselective with respect to charge. In Cx26/Cx32 heterotypic cell pairs, the macroscopic fast rectification of the current-voltage relationship was fully explained at the single-channel level by a rectifying gamma(j) that increased by a factor of 2.9 as the transjunctional voltage (V(j)) changed from -100 to +100 mV with the Cx26 cell as the positive pole. A model of electrodiffusion of ions through the gap junction pore based on Nernst-Planck equations for ion concentrations and the Poisson equation for the electrical potential within the junction is developed. Selectivity characteristics are ascribed to each hemichannel based on either pore features (treated as uniform along the length of the hemichannel) or entrance effects unique to each connexin. Both analytical GHK approximations and full numerical solutions predict rectifying characteristics for Cx32/Cx26 heterotypic channels, although not to the full extent seen empirically. The model predicts that asymmetries in the conductance/permeability properties of the hemichannels (also cast as Donnan potentials) will produce either an accumulation or a depletion of ions within the channel, depending on voltage polarity, that will result in rectification.
Barrio,
Gap junctions formed by connexins 26 and 32 alone and in combination are differently affected by applied voltage.
1991, Pubmed,
Xenbase
Barrio,
Gap junctions formed by connexins 26 and 32 alone and in combination are differently affected by applied voltage.
1991,
Pubmed
,
Xenbase Beblo,
Monovalent cation permeation through the connexin40 gap junction channel. Cs, Rb, K, Na, Li, TEA, TMA, TBA, and effects of anions Br, Cl, F, acetate, aspartate, glutamate, and NO3.
1997,
Pubmed Bevans,
Isoform composition of connexin channels determines selectivity among second messengers and uncharged molecules.
1998,
Pubmed Brink,
Evidence for fixed charge in the nexus.
1980,
Pubmed Brink,
Evidence for heteromeric gap junction channels formed from rat connexin43 and human connexin37.
1997,
Pubmed Bruzzone,
Connections with connexins: the molecular basis of direct intercellular signaling.
1996,
Pubmed Bukauskas,
Heterotypic gap junction channels (connexin26-connexin32) violate the paradigm of unitary conductance.
1995,
Pubmed Cao,
A quantitative analysis of connexin-specific permeability differences of gap junctions expressed in HeLa transfectants and Xenopus oocytes.
1998,
Pubmed
,
Xenbase Chen,
Constant fields and constant gradients in open ionic channels.
1992,
Pubmed Chen,
Flux, coupling, and selectivity in ionic channels of one conformation.
1993,
Pubmed Dahl,
Molecular cloning and functional expression of mouse connexin-30,a gap junction gene highly expressed in adult brain and skin.
1996,
Pubmed
,
Xenbase Dunlap,
Activation of a calcium-dependent photoprotein by chemical signalling through gap junctions.
,
Pubmed Eisenberg,
Computing the field in proteins and channels.
1996,
Pubmed Elfgang,
Specific permeability and selective formation of gap junction channels in connexin-transfected HeLa cells.
1995,
Pubmed Falk,
Cell-free synthesis and assembly of connexins into functional gap junction membrane channels.
1997,
Pubmed Flagg-Newton,
Cell junction and cyclic AMP: 1. Upregulation of junctional membrane permeability and junctional membrane particles by administration of cyclic nucleotide or phosphodiesterase inhibitor.
1981,
Pubmed FRANKENHAEUSER,
Sodium permeability in toad nerve and in squid nerve.
1960,
Pubmed Fuhlbrigge,
Expression of membrane interleukin 1 by fibroblasts transfected with murine pro-interleukin 1 alpha cDNA.
1988,
Pubmed Harris,
Ion channels in single bilayers induced by rat connexin32.
1992,
Pubmed Hennemann,
Molecular cloning and functional expression of mouse connexin40, a second gap junction gene preferentially expressed in lung.
1992,
Pubmed
,
Xenbase HODGKIN,
The effect of sodium ions on the electrical activity of giant axon of the squid.
1949,
Pubmed Horan,
Fluorescent cell labeling for in vivo and in vitro cell tracking.
1990,
Pubmed Horn,
Run, don't hop, through the nearest calcium channel.
1998,
Pubmed Jaslove,
The mechanism of rectification at the electrotonic motor giant synapse of the crayfish.
,
Pubmed Jiang,
Heteromeric connexons in lens gap junction channels.
1996,
Pubmed
,
Xenbase Kumar,
The gap junction communication channel.
1996,
Pubmed Levitt,
General continuum theory for multiion channel. II. Application to acetylcholine channel.
1991,
Pubmed Makowski,
Gap junction structures. V. Structural chemistry inferred from X-ray diffraction measurements on sucrose accessibility and trypsin susceptibility.
1984,
Pubmed Moreno,
Connexin32 gap junction channels in stably transfected cells: unitary conductance.
1991,
Pubmed Neveu,
Multiple mechanisms are responsible for altered expression of gap junction genes during oncogenesis in rat liver.
1994,
Pubmed Nicholson,
Two homologous protein components of hepatic gap junctions.
,
Pubmed Nonner,
Ion permeation and glutamate residues linked by Poisson-Nernst-Planck theory in L-type calcium channels.
1998,
Pubmed Paul,
Molecular cloning of cDNA for rat liver gap junction protein.
1986,
Pubmed Reed,
Molecular cloning and functional expression of human connexin37, an endothelial cell gap junction protein.
1993,
Pubmed Sáez,
Hepatocyte gap junctions are permeable to the second messenger, inositol 1,4,5-trisphosphate, and to calcium ions.
1989,
Pubmed Schwarzmann,
Diameter of the cell-to-cell junctional membrane channels as probed with neutral molecules.
1981,
Pubmed Spray,
Equilibrium properties of a voltage-dependent junctional conductance.
1981,
Pubmed
,
Xenbase Stauffer,
The gap junction proteins beta 1-connexin (connexin-32) and beta 2-connexin (connexin-26) can form heteromeric hemichannels.
1995,
Pubmed Steinberg,
Connexin43 and connexin45 form gap junctions with different molecular permeabilities in osteoblastic cells.
1994,
Pubmed Traub,
Comparative characterization of the 21-kD and 26-kD gap junction proteins in murine liver and cultured hepatocytes.
1989,
Pubmed Tsien,
Inotropic effect of cyclic AMP in calf ventricular muscle studied by a cut end method.
1976,
Pubmed Veenstra,
Selectivity of connexin-specific gap junctions does not correlate with channel conductance.
1995,
Pubmed Veenstra,
Size and selectivity of gap junction channels formed from different connexins.
1996,
Pubmed Veenstra,
Connexin37 forms high conductance gap junction channels with subconductance state activity and selective dye and ionic permeabilities.
1994,
Pubmed Verselis,
Opposite voltage gating polarities of two closely related connexins.
1994,
Pubmed
,
Xenbase Verselis,
The gap junction channel. Its aqueous nature as indicated by deuterium oxide effects.
1986,
Pubmed Wang,
Monovalent ion selectivity sequences of the rat connexin43 gap junction channel.
1997,
Pubmed White,
Mouse Cx50, a functional member of the connexin family of gap junction proteins, is the lens fiber protein MP70.
1992,
Pubmed
,
Xenbase White,
Functional analysis of selective interactions among rodent connexins.
1995,
Pubmed
,
Xenbase Yeager,
Structure of gap junction intercellular channels.
1996,
Pubmed Zhang,
The topological structure of connexin 26 and its distribution compared to connexin 32 in hepatic gap junctions.
1994,
Pubmed
