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.
???displayArticle.abstract???
The substituted cysteine accessibility method was applied to single Cx46 hemichannels to identify residues that participate in lining the aqueous pore of channels formed of connexins. Criteria for assignment to the pore included reactivity to sulfydryl-specific methanethiosulfonate (MTS) reagents from both sides of an open hemichannel and observable effects on open channel properties. We demonstrate reactivity to MTS reagents over a stretch of seventeen amino acids, D51 through L35, that constitute segments of E1 and TM1. Qualitatively, the nature of the effects caused by the Cys substitutions alone and their modification with MTS reagents of either charge indicate side chain valence is most influential in determining single channel properties with D51 and L35 defining the extracellular and intracellular limits, respectively, of the identified pore-lining region. A number of Cys substitutions beyond L35 in TM1 caused severe alterations in hemichannel function and precluded assignment to the pore. Although all six subunits can be modified by smaller MTS reagents, modifications appear limited to fewer subunits with larger reagents.
Bennett,
Gap junctions: new tools, new answers, new questions.
1991, Pubmed
Bennett,
Gap junctions: new tools, new answers, new questions.
1991,
Pubmed
Cha,
Structural implications of fluorescence quenching in the Shaker K+ channel.
1998,
Pubmed
Cheng,
Projection structure of full length connexin 43 by electron cryo-crystallography.
2003,
Pubmed
Foote,
The pattern of disulfide linkages in the extracellular loop regions of connexin 32 suggests a model for the docking interface of gap junctions.
1998,
Pubmed
,
Xenbase
Horn,
Coupled movements in voltage-gated ion channels.
2002,
Pubmed
Karlin,
Substituted-cysteine accessibility method.
1998,
Pubmed
Kronengold,
Single-channel SCAM identifies pore-lining residues in the first extracellular loop and first transmembrane domains of Cx46 hemichannels.
2003,
Pubmed
,
Xenbase
Musa,
Voltage-dependent blockade of connexin40 gap junctions by spermine.
2003,
Pubmed
Pfahnl,
Localization of a voltage gate in connexin46 gap junction hemichannels.
1998,
Pubmed
,
Xenbase
Skerrett,
Identification of amino acid residues lining the pore of a gap junction channel.
2002,
Pubmed
,
Xenbase
Srinivas,
Functional properties of channels formed by the neuronal gap junction protein connexin36.
1999,
Pubmed
Teubner,
Functional expression of the murine connexin 36 gene coding for a neuron-specific gap junctional protein.
2000,
Pubmed
,
Xenbase
Trexler,
Voltage gating and permeation in a gap junction hemichannel.
1996,
Pubmed
,
Xenbase
Trexler,
The first extracellular loop domain is a major determinant of charge selectivity in connexin46 channels.
2000,
Pubmed
,
Xenbase
Unger,
Three-dimensional structure of a recombinant gap junction membrane channel.
1999,
Pubmed
Verselis,
Opposite voltage gating polarities of two closely related connexins.
1994,
Pubmed
,
Xenbase
Zhou,
Identification of a pore lining segment in gap junction hemichannels.
1997,
Pubmed
,
Xenbase
Zhou,
Chemistry of ion coordination and hydration revealed by a K+ channel-Fab complex at 2.0 A resolution.
2001,
Pubmed