Pannexins or connexins?

Gerhard Dahl, Andrew L. Harris

Research output: Chapter in Book/Report/Conference proceedingChapter

13 Scopus citations


Pannexins are a family of three vertebrate proteins that have moderate sequence homology with the innexin proteins, which compose gap junction channels in protostomes, including most invertebrates. However, it appears that in contrast to innexins, pannexins do not have the ability to form gap junction channels. They do, however, form nonjunctional plasma membrane channels (pannexons) that mediate regulated flux of molecules in the size range of second messengers between cytoplasm and the extracellular space. The dye permeability and pharmacological sensitivities of pannexin channels overlap those of connexin hemichannels, so it is possible that many of the phenomena that have been attributed to connexin hemichannels are in fact mediated by pannexons. For this reason, identifying which protein is involved in a particular cellular physiology requires careful evaluation of the specific conditions and requirements in each case. Several lines of experimentation have led to the suggestion that the adenosine triphosphate (ATP) release channel, a crucial element in the initiation and propagation of intercellular Ca2+ waves, is a connexin hemichannel. However, based on recently revealed properties of pannexin channels, which include mechanosensitivity and activation by cytoplasmic Ca2+, the pannexon must be considered a prime candidate for the ATP release channel. Pannexons also appear to form the large ATP-permeable pore that is activated by the purinergic P2X7 receptor complex, which is involved in inflammation.

Original languageEnglish (US)
Title of host publicationConnexins
Subtitle of host publicationA Guide
PublisherHumana Press Inc.
Number of pages15
ISBN (Electronic)9781597454896
ISBN (Print)9781934115466
StatePublished - Jan 1 2009


  • ATP release
  • Calcium wave
  • Connexin
  • Cx32
  • Cx38
  • Cx43
  • Gap junction
  • Hemichannel
  • Innexin
  • P2X7 receptor
  • P2Y receptor
  • Pannexin
  • Pannexon

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)


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