Size selectivity between gap junction channels composed of different connexins

Xiang Qun Gong, Bruce J. Nicholson

Research output: Contribution to journalArticlepeer-review

38 Scopus citations


Gap junction channels are traditionally viewed as large, nonspecific pores connecting cells. Recently the diversity in the connexin family has drawn more attention to their permeability characteristics. Several studies have shown that both size and charge contribute to the permeability of gap junctional channels. We have used a graded series of neutral polyethylene glycol probes (PEGs), which eliminate charge contribution completely, to specifically assess the physical exclusion limits of gap junction channels formed by different connexins. Cx 26, 32 and 37 were expressed in paired Xenopus oocytes to form homotypic gap junctional channels. PEG probes were perfused intracellularly into one side of the oocyte pair. A reversible drop in conductance of the gap juctional channels indicated that the probe was small enough to enter the pore and binder ion flux. Our data suggest that Cx32 channels have a size cut-off between PEG 400 (11.2 Å) and PEG 300 (9.6 Å) despite their relatively small single channel conductance (∼55pS). Cx26 channels (∼130pS single channel conductance) have a size exclusion limit around PEG 200 (8.0 Å), while Cx37 channels show the most restricted size cut-off between PEG 200 (8.0 Å) and TriEG (6.8 Å), despite having the largest unitary conductance (∼300pS).

Original languageEnglish (US)
Pages (from-to)187-192
Number of pages6
JournalCell Communication and Adhesion
Issue number4-6
StatePublished - 2001
Externally publishedYes


  • Connexin
  • Neutral probe
  • Perfusion
  • Polyethylene glycols
  • Size selectivity

ASJC Scopus subject areas

  • Clinical Biochemistry
  • Cell Biology


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