2008/11/07 by Gerhard Dahl, Andrew L. Harris · 1 citation
Biochemistry, Genetics and Molecular Biology · Medicine · #Connexins and lens biology #Nicotinic Acetylcholine Receptors Study #Biochemical effects in animals
paper · doi:10.1007/978-1-59745-489-6_12
openalex publication_date 2008/11/07 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/04
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 Ca 2+ waves, is a connexin hemichannel. However, based on recently revealed properties of pannexin channels, which include mechanosensitivity and activation by cytoplasmic Ca 2+ , 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.