Conductance and permeability of the residual state of connexin43 gap junction channels

Feliksas F. Bukauskas, Angele Bukauskiene, Vytas K. Verselis

Research output: Contribution to journalArticle

64 Scopus citations

Abstract

We used cell lines expressing wild-type connexin43 and connexin43 fused with the enhanced green fluorescent protein (Cx43-EGFP) to examine conductance and perm-selectivity of the residual state of Cx43 homotypic and Cx43/Cx43-EGFP heterotypic gap junction channels. Each hemichannel in Cx43 cell-cell channel possesses two gates: a fast gate that closes channels to the residual state and a slow gate that fully closes channels; the transjunctional voltage (Vj) closes the fast gate in the hemichannel that is on the relatively negative side. Here, we demonstrate macroscopically and at the single-channel level that the I-V relationship of the residual state rectifies, exhibiting higher conductance at higher Vjs that are negative on the side of gated hemichannel. The degree of rectification increases when Cl- is replaced by Asp- and decreases when K+ is replaced by TEA+. These data are consistent with an increased anionic selectivity of the residual state. The Vj-gated channel is not permeable to monovalent positively and negatively charged dyes, which are readily permeable through the fully open channel. These data indicate that a narrowing of the channel pore accompanies gating to the residual state. We suggest that the fast gate operates through a conformational change that introduces positive charge at the cytoplasmic vestibule of the gated hemichannel, thereby producing current rectification, increased anionic selectivity, and a narrowing of channel pore that is largely responsible for reducing channel conductance and restricting dye transfer. Consequently, the fast Vj-sensitive gating mechanism can serve as a selectivity filter, which allows electrical coupling but limits metabolic communication.

Original languageEnglish (US)
Pages (from-to)171-185
Number of pages15
JournalJournal of General Physiology
Volume119
Issue number2
DOIs
StatePublished - 2002

Keywords

  • Dye transfer
  • EGFP
  • Intercellular communication
  • Permeability
  • Voltage gating

ASJC Scopus subject areas

  • Physiology

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