Switch to
| Predicate | Object |
|---|---|
| rdf:type | |
| lifeskim:mentions | |
| pubmed:issue |
6
|
| pubmed:dateCreated |
1995-12-26
|
| pubmed:abstractText |
Connexins form a variety of gap junction channels that vary in their developmental and tissue-specific levels of expression, modulation of gating by transjunctional voltage and posttranslational modification, and unitary channel conductance (gamma j). Despite a 10-fold variation in gamma j, whether connexin-specific channels possess distinct ionic and molecular permeabilities is presently unknown. A major assumption of the conventional model for a gap junction channel pore is that gamma j is determined primarily by pore diameter. Hence, molecular size permeability limits should increase and ionic selectivity should decrease with increasing channel gamma j (and pore diameter). Equimolar ion substitution of 120 mmol/L KCl for potassium glutamate was used to determine the unitary conductance ratios for rat connexin40 and connexin43, chicken connexin43 and connexin45, and human connexin37 channels functionally expressed in communication-deficient mouse neuroblastoma (N2A) cells. Comparison of experimental and predicted conductance ratios based on the aqueous mobilities of all ions according to the Goldman-Hodgkin-Katz current equation was used to determine relative anion-to-cation permeability ratios. Direct correlation of junctional conductance with dye transfer of two fluorescein-derivatives (2 mmol/L 6-carboxyfluorescein or 2',7'-dichlorofluorescein) was also performed. Both approaches revealed a range of selectivities and permeabilities for all five different connexins that was independent of channel conductance. These results are not consistent with the conventional simple aqueous pore model of a gap junction channel and suggest a new model for connexin channel conductance and permselectivity based on electrostatic interactions. Divergent conductance and permeability properties are features of other classes of ion channels (eg, Na+ and K+ channels), implying similar mechanisms for selectivity.
|
| pubmed:language |
eng
|
| pubmed:journal | |
| pubmed:citationSubset |
IM
|
| pubmed:chemical |
http://linkedlifedata.com/resource/pubmed/chemical/1,2-dielaidoylphosphatidylethanolami...,
http://linkedlifedata.com/resource/pubmed/chemical/2',7'-dichlorofluorescein,
http://linkedlifedata.com/resource/pubmed/chemical/6-carboxyfluorescein,
http://linkedlifedata.com/resource/pubmed/chemical/Connexins,
http://linkedlifedata.com/resource/pubmed/chemical/Fluoresceins,
http://linkedlifedata.com/resource/pubmed/chemical/Fluorescent Dyes,
http://linkedlifedata.com/resource/pubmed/chemical/Ion Channels,
http://linkedlifedata.com/resource/pubmed/chemical/Liposomes,
http://linkedlifedata.com/resource/pubmed/chemical/Phosphatidylethanolamines
|
| pubmed:status |
MEDLINE
|
| pubmed:month |
Dec
|
| pubmed:issn |
0009-7330
|
| pubmed:author | |
| pubmed:issnType |
Print
|
| pubmed:volume |
77
|
| pubmed:owner |
NLM
|
| pubmed:authorsComplete |
Y
|
| pubmed:pagination |
1156-65
|
| pubmed:dateRevised |
2006-11-15
|
| pubmed:meshHeading |
pubmed-meshheading:7586229-Animals,
pubmed-meshheading:7586229-Blotting, Northern,
pubmed-meshheading:7586229-Cells, Cultured,
pubmed-meshheading:7586229-Chickens,
pubmed-meshheading:7586229-Connexins,
pubmed-meshheading:7586229-Diffusion,
pubmed-meshheading:7586229-Electric Conductivity,
pubmed-meshheading:7586229-Electrophysiology,
pubmed-meshheading:7586229-Fluoresceins,
pubmed-meshheading:7586229-Fluorescent Dyes,
pubmed-meshheading:7586229-Gap Junctions,
pubmed-meshheading:7586229-Genetic Vectors,
pubmed-meshheading:7586229-Humans,
pubmed-meshheading:7586229-Ion Channels,
pubmed-meshheading:7586229-Liposomes,
pubmed-meshheading:7586229-Mice,
pubmed-meshheading:7586229-Models, Anatomic,
pubmed-meshheading:7586229-Models, Biological,
pubmed-meshheading:7586229-Molecular Weight,
pubmed-meshheading:7586229-Neuroblastoma,
pubmed-meshheading:7586229-Patch-Clamp Techniques,
pubmed-meshheading:7586229-Phosphatidylethanolamines,
pubmed-meshheading:7586229-Plasmids,
pubmed-meshheading:7586229-Rats,
pubmed-meshheading:7586229-Second Messenger Systems,
pubmed-meshheading:7586229-Surface Properties,
pubmed-meshheading:7586229-Transfection
|
| pubmed:year |
1995
|
| pubmed:articleTitle |
Selectivity of connexin-specific gap junctions does not correlate with channel conductance.
|
| pubmed:affiliation |
Department of Pharmacology, State University of New York Health Science Center at Syracuse 13210, USA.
|
| pubmed:publicationType |
Journal Article,
Comparative Study,
Research Support, U.S. Gov't, P.H.S.,
Research Support, U.S. Gov't, Non-P.H.S.,
Research Support, Non-U.S. Gov't
|