Neurons and β-cells of the pancreas express connexin36, forming gap junction channels that exhibit strong cationic selectivity

Feliksas F. Bukauskas

Research output: Contribution to journalArticle

14 Scopus citations

Abstract

We examined the permeability of connexin36 (Cx36) homotypic gap junction (GJ) channels, expressed in neurons and β-cells of the pancreas, to dyes differing in molecular mass and net charge. Experiments were performed in HeLa cells stably expressing Cx36 tagged with EGFP by combining a dual whole-cell voltage clamp and fluorescence imaging. To assess the permeability of the single GJ channel (Pγ), we used a dual-mode excitation of fluorescent dyes that allowed us to measure cell-to-cell dye transfer at levels not resolvable using whole-field excitation solely. We demonstrate that P γ of Cx36 for cationic dyes (EAM-1+ and EAM-2 +) is ~10-fold higher than that for an anionic dye of the same net charge and similar molecular mass, Alexa fluor-350 (AFl-350-). In addition, Pγ for Lucifer yellow (LY2-) is approximately fourfold smaller than that for AFl-350-, which suggests that the higher negativity of LY2- significantly reduces permeability. The Pγ of Cx36 for AFl-350 is approximately 358, 138, 23 and four times smaller than the Pγs of Cx43, Cx40, Cx45, and Cx57, respectively. In contrast, it is 6.5-fold higher than the P γ of mCx30.2, which exhibits a smaller single-channel conductance. Thus, Cx36 GJs are highly cation-selective and should exhibit relatively low permeability to numerous vital negatively charged metabolites and high permeability to K+, a major charge carrier in cell-cell communication.

Original languageEnglish (US)
Pages (from-to)243-253
Number of pages11
JournalJournal of Membrane Biology
Volume245
Issue number5-6
DOIs
StatePublished - Jun 1 2012

Keywords

  • Cationic selectivity
  • Connexin
  • Gap junction
  • Intercellular communication
  • Permeability
  • Voltage gating

ASJC Scopus subject areas

  • Biophysics
  • Physiology
  • Cell Biology

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