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PMID: 9129799 Published · ppublish English Journal Article Research Support, U.S. Gov't, P.H.S.

Identification of a pore lining segment in gap junction hemichannels.

Biophysical journal ·Vol. 72 ·No. 5 ·1997-05-00 ·Pages 1946-53

Zhou XW, Pfahnl A, Werner R, Hudder A, Llanes A, Luebke A, Dahl G

Abstract

The ability of certain connexins to form open hemichannels has been exploited to study the pore structure of gap junction (hemi)channels. Cysteine scanning mutagenesis was applied to cx46 and to a chimeric connexin, cx32E(1)43, which both form patent hemichannels when expressed in Xenopus oocytes. The thiol reagent maleimido-butyryl-biocytin was used to probe 12 cysteine replacement mutants in the first transmembrane segment and two in the amino-terminal segment. Maleimido-butyryl-biocytin was found to inhibit channel activity with cysteines in two equivalent positions in both connexins: I33C and M34C in cx32E(1)43 and I34C and L35C in cx46. These two positions in the first transmembrane segment are thus accessible from the extracellular space and consequently appear to contribute to the pore lining. The data also suggest that the pore structure is complex and may involve more than one transmembrane segment.

MeSH Terms
Amino Acid Sequence Animals Connexins/chemistry Cysteine/chemistry Gap Junctions/chemistry Lysine/analogs & derivatives,chemistry Maleimides/chemistry Mutagenesis Oocytes Porins/chemistry Protein Conformation Sequence Homology, Amino Acid Xenopus
Chemicals
Connexins Maleimides Porins biocytin Lysine Cysteine
Authors & Affiliations
7 authors, click to expand affiliations / ORCID
Zhou X W
Department of Physiology and Biophysics, University of Miami School of Medicine, Florida 33101, USA.
Pfahnl A
Werner R
Hudder A
Llanes A
Luebke A
Dahl G
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Article Info
Journal
Biophysical journal
Abbr.
Biophys J
ISSN
0006-3495
DOI
10.1016/S0006-3495(97)78840-4
Published
1997-05-00
Pages
1946-53
Language
English
Region
United States
NLM ID
0370626
PMCID
PMC1184391
Subset
IM
Grants
NIDCD NIH HHS · R01 DC003086 · United States
NIGMS NIH HHS · GM 40583 · United States
NIGMS NIH HHS · GM48610 · United States
External Links
PubMed source DOI: 10.1016/S0006-3495(97)78840-4 PMC Full Text View journal details
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