Affordable Access

Access to the full text

Neurons and β-Cells of the Pancreas Express Connexin36, Forming Gap Junction Channels that Exhibit Strong Cationic Selectivity

Authors
  • Bukauskas, Feliksas F.1
  • 1 Albert Einstein College of Medicine, Dominick P. Purpura Department of Neuroscience, 1300 Morris Park Avenue, Bronx, NY, 10461, USA , Bronx (United States)
Type
Published Article
Journal
The Journal of Membrane Biology
Publisher
Springer-Verlag
Publication Date
Jun 30, 2012
Volume
245
Issue
5-6
Pages
243–253
Identifiers
DOI: 10.1007/s00232-012-9445-3
Source
Springer Nature
Keywords
License
Yellow

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 Pγ 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 Pγ 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.

Report this publication

Statistics

Seen <100 times