Identification of a pore lining segment in gap junction hemichannels

Xiao Wei Zhou, Arnold Pfahnl, Rudolf Werner, Alice Hudder, Audrey Llanes, Anne Luebke, Gerhard Dahl

Research output: Contribution to journalArticlepeer-review

108 Scopus citations


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, cx32E143, 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: 133C and M34C in cx32E143 and 134C 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.

Original languageEnglish (US)
Pages (from-to)1946-1953
Number of pages8
JournalBiophysical journal
Issue number5
StatePublished - May 1997

ASJC Scopus subject areas

  • Biophysics


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