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Hemichannel and junctional properties of connexin 50.
Beahm DL
,
Hall JE
.
???displayArticle.abstract??? Lens fiber connexins, cx50 and cx46 (alpha3 and alpha8), belong to a small subset of connexins that can form functional hemichannels in nonjunctional membranes. Knockout of either cx50 or cx46 results in a cataract, so the properties of both connexins are likely essential for proper physiological functioning of the lens. Although portions of the sequences of these two connexins are nearly identical, their hemichannel properties are quite different. Cx50 hemichannels are much more sensitive to extracellular acidification than cx46 hemichannels and differ from cx46 hemichannels both in steady-state and kinetic properties. Comparison of the two branches of the cx50 hemichannel G-V curve with the junctional G-V curve suggests that cx50 gap junctions gate with positive relative polarity. The histidine-modifying reagent, diethyl pyrocarbonate, reversibly blocks cx50 hemichannel currents but not cx46 hemichannel currents. Because cx46 and cx50 have very similar amino acid sequences, one might expect that replacing the two histidines unique to the third transmembrane region of cx50 with the corresponding cx46 residues would produce mutants more closely resembling cx46. In fact this does not happen. Instead the mutant cx50H161N does not form detectable hemichannels but forms gap junctions indistinguishable from wild type. Cx50H176Q is oocyte lethal, and the double mutant, cx50H61N/H176Q, neither forms hemichannels nor kills oocytes.
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
Bassnett,
The influence of pH on membrane conductance and intercellular resistance in the rat lens.
1988,
Pubmed
Bruzzone,
Connexin40, a component of gap junctions in vascular endothelium, is restricted in its ability to interact with other connexins.
1993,
Pubmed
,
Xenbase
Bukauskas,
Clustering of connexin 43-enhanced green fluorescent protein gap junction channels and functional coupling in living cells.
2000,
Pubmed
Dahl,
Attempts to define functional domains of gap junction proteins with synthetic peptides.
1994,
Pubmed
,
Xenbase
DeVries,
Hemi-gap-junction channels in solitary horizontal cells of the catfish retina.
1992,
Pubmed
Dunham,
Immunolocalization and expression of functional and nonfunctional cell-to-cell channels from wild-type and mutant rat heart connexin43 cDNA.
1992,
Pubmed
,
Xenbase
Ebihara,
Properties of a nonjunctional current expressed from a rat connexin46 cDNA in Xenopus oocytes.
1993,
Pubmed
,
Xenbase
Ebihara,
Distinct behavior of connexin56 and connexin46 gap junctional channels can be predicted from the behavior of their hemi-gap-junctional channels.
1995,
Pubmed
,
Xenbase
Eckert,
A distinct membrane current in rat lens fiber cells isolated under calcium-free conditions.
1998,
Pubmed
,
Xenbase
Ek,
Role of histidine 95 on pH gating of the cardiac gap junction protein connexin43.
1994,
Pubmed
,
Xenbase
Gong,
Disruption of alpha3 connexin gene leads to proteolysis and cataractogenesis in mice.
1997,
Pubmed
Goodenough,
Topological distribution of two connexin32 antigenic sites in intact and split rodent hepatocyte gap junctions.
1988,
Pubmed
Gupta,
Bovine connexin44, a lens gap junction protein: molecular cloning, immunologic characterization, and functional expression.
1994,
Pubmed
,
Xenbase
Hennemann,
Molecular cloning and functional expression of mouse connexin40, a second gap junction gene preferentially expressed in lung.
1992,
Pubmed
,
Xenbase
Jedamzik,
Regulation of lens rCx46-formed hemichannels by activation of protein kinase C, external Ca(2+) and protons.
2000,
Pubmed
,
Xenbase
Laird,
Biochemical and immunochemical analysis of the arrangement of connexin43 in rat heart gap junction membranes.
1990,
Pubmed
Liu,
A structural basis for the unequal sensitivity of the major cardiac and liver gap junctions to intracellular acidification: the carboxyl tail length.
1993,
Pubmed
,
Xenbase
Mathias,
Cell to cell communication and pH in the frog lens.
1991,
Pubmed
Mathias,
Steady state voltages in the frog lens.
1985,
Pubmed
Mathias,
The localization of transport properties in the frog lens.
1985,
Pubmed
Mathias,
Physiological properties of the normal lens.
1997,
Pubmed
Mathias,
Electrical properties of structural components of the crystalline lens.
1979,
Pubmed
Miles,
Modification of histidyl residues in proteins by diethylpyrocarbonate.
1977,
Pubmed
Milks,
Topology of the 32-kd liver gap junction protein determined by site-directed antibody localizations.
1988,
Pubmed
Morley,
Intramolecular interactions mediate pH regulation of connexin43 channels.
1996,
Pubmed
,
Xenbase
Németh-Cahalan,
pH and calcium regulate the water permeability of aquaporin 0.
2000,
Pubmed
,
Xenbase
Padan,
Effect of diethylpyrocarbonate on lactose/proton symport in Escherichia coli membrane vesicles.
1979,
Pubmed
Pasquale,
Electrostatic properties of fiber cell membranes from the frog lens.
1990,
Pubmed
Paul,
Connexin46, a novel lens gap junction protein, induces voltage-gated currents in nonjunctional plasma membrane of Xenopus oocytes.
1991,
Pubmed
,
Xenbase
Pfahnl,
Localization of a voltage gate in connexin46 gap junction hemichannels.
1998,
Pubmed
,
Xenbase
Pfahnl,
Gating of cx46 gap junction hemichannels by calcium and voltage.
1999,
Pubmed
,
Xenbase
Rai,
Localization of critical histidyl residues required for vinblastine-induced tubulin polymerization and for microtubule assembly.
1998,
Pubmed
Shoshan-Barmatz,
Diethyl pyrocarbonate modification of the ryanodine receptor/Ca2+ channel from skeletal muscle.
1994,
Pubmed
Spires,
Modification of potassium channel kinetics by histidine-specific reagents.
1990,
Pubmed
Trexler,
Voltage gating and permeation in a gap junction hemichannel.
1996,
Pubmed
,
Xenbase
White,
Selective interactions among the multiple connexin proteins expressed in the vertebrate lens: the second extracellular domain is a determinant of compatibility between connexins.
1994,
Pubmed
,
Xenbase
White,
Voltage gating of connexins.
1994,
Pubmed
,
Xenbase
White,
Functional analysis of selective interactions among rodent connexins.
1995,
Pubmed
,
Xenbase
White,
Targeted ablation of connexin50 in mice results in microphthalmia and zonular pulverulent cataracts.
1998,
Pubmed
Wilders,
Limitations of the dual voltage clamp method in assaying conductance and kinetics of gap junction channels.
1992,
Pubmed
Yeager,
Membrane topology and quaternary structure of cardiac gap junction ion channels.
1992,
Pubmed
Zampighi,
Functional and morphological correlates of connexin50 expressed in Xenopus laevis oocytes.
1999,
Pubmed
,
Xenbase