Click here to close
Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly.
We suggest using a current version of Chrome,
FireFox, or Safari.
Accessibility of cx46 hemichannels for uncharged molecules and its modulation by voltage.
Qu Y, Dahl G.
???displayArticle.abstract???
Excised patches of oocyte membrane containing cx46 hemichannels were used to determine the accessibility of the channels for several uncharged molecules at negative and positive holding potentials. The molecular weights of the test molecules (sugars and polyethylene glycols) ranged from 180 to 666 Daltons, with diameters from 5.8 to 12 A. Activation of the voltage gate (V(j) gate) at positive potentials shifted the accessibility limit for these test molecules to lower sizes indicating that net charge of the test molecule does not determine accessibility. The sugars changed several channel properties: 1), single-channel conductance decreased in an inverse relationship to the size of the test molecule; 2), the apparent open probability of the connexin channels was reduced; 3), the lifetimes of the apparent occupancy states exceeded the expected transit times assuming simple diffusion by orders of magnitude. These results suggest a channel that is not cylindrical and in which test molecules bind or are trapped in the pore or the vestibulum. Furthermore, the effect of sugars and the large difference in transit rates for small ions and larger molecules suggest that they may involve different permeation mechanisms.
Bezrukov,
Probing sugar translocation through maltoporin at the single channel level.
2000, Pubmed
Bezrukov,
Probing sugar translocation through maltoporin at the single channel level.
2000,
Pubmed Bezrukov,
Ion channels as molecular coulter counters to probe metabolite transport.
2000,
Pubmed Bezrukov,
Counting polymers moving through a single ion channel.
1994,
Pubmed Bezrukov,
Probing alamethicin channels with water-soluble polymers. Effect on conductance of channel states.
1993,
Pubmed Evans,
Gap junctions: structure and function (Review).
2002,
Pubmed Gong,
Size selectivity between gap junction channels composed of different connexins.
2001,
Pubmed
,
Xenbase Hamill,
Improved patch-clamp techniques for high-resolution current recording from cells and cell-free membrane patches.
1981,
Pubmed Harris,
Emerging issues of connexin channels: biophysics fills the gap.
2001,
Pubmed Krasilnikov,
A simple method for the determination of the pore radius of ion channels in planar lipid bilayer membranes.
1992,
Pubmed Krasilnikov,
The diameter of water pores formed by colicin Ia in planar lipid bilayers.
1995,
Pubmed Kullman,
Transport of maltodextrins through maltoporin: a single-channel study.
2002,
Pubmed Merzlyak,
Polymeric nonelectrolytes to probe pore geometry: application to the alpha-toxin transmembrane channel.
1999,
Pubmed Oh,
Stoichiometry of transjunctional voltage-gating polarity reversal by a negative charge substitution in the amino terminus of a connexin32 chimera.
2000,
Pubmed
,
Xenbase Oh,
Changes in permeability caused by connexin 32 mutations underlie X-linked Charcot-Marie-Tooth disease.
1997,
Pubmed
,
Xenbase Parsegian,
Watching small molecules move: interrogating ionic channels using neutral solutes.
1995,
Pubmed Paul,
Connexin46, a novel lens gap junction protein, induces voltage-gated currents in nonjunctional plasma membrane of Xenopus oocytes.
1991,
Pubmed
,
Xenbase Pfahnl,
A chimeric connexin forming gap junction hemichannels.
1997,
Pubmed
,
Xenbase Pfahnl,
Localization of a voltage gate in connexin46 gap junction hemichannels.
1998,
Pubmed
,
Xenbase Qu,
Function of the voltage gate of gap junction channels: selective exclusion of molecules.
2002,
Pubmed
,
Xenbase Sabirov,
Relation between ionic channel conductance and conductivity of media containing different nonelectrolytes. A novel method of pore size determination.
1993,
Pubmed Spray,
Equilibrium properties of a voltage-dependent junctional conductance.
1981,
Pubmed
,
Xenbase Trexler,
Voltage gating and permeation in a gap junction hemichannel.
1996,
Pubmed
,
Xenbase Unger,
Three-dimensional structure of a recombinant gap junction membrane channel.
1999,
Pubmed Valiunas,
Biophysical properties of connexin-45 gap junction hemichannels studied in vertebrate cells.
2002,
Pubmed Veenstra,
Size and selectivity of gap junction channels formed from different connexins.
1996,
Pubmed Veenstra,
Selectivity of connexin-specific gap junctions does not correlate with channel conductance.
1995,
Pubmed Zampighi,
Functional and morphological correlates of connexin50 expressed in Xenopus laevis oocytes.
1999,
Pubmed
,
Xenbase Zhou,
Identification of a pore lining segment in gap junction hemichannels.
1997,
Pubmed
,
Xenbase Zimmerberg,
Solute inaccessible aqueous volume changes during opening of the potassium channel of the squid giant axon.
1990,
Pubmed
