title: Pannexin channels are not gap junction hemichannels.
abstract: Pannexins, a class of membrane channels, bear significant sequence homology with the invertebrate gap junction proteins, innexins and more distant similarities in their membrane topologies and pharmacological sensitivities with the gap junction proteins, connexins. However, the functional role for the pannexin oligomers, or pannexons, is different from connexin oligomers, the connexons. Many pannexin publications have used the term "hemichannels" to describe pannexin oligomers while others use the term "channels" instead. This has led to confusion within the literature about the function of pannexins that promotes the idea that pannexons serve as gap junction hemichannels and thus have an assembly and functional state as gap junctional intercellular channels. Here we present the case that unlike the connexin gap junction intercellular channels, so far, pannexin oligomers have repeatedly been shown to be channels that are functional in single membranes, but not as intercellular channel in appositional membranes. Hence, they should be referred to as channels and not hemichannels. Thus, we advocate that in the absence of firm evidence that pannexins form gap junctions, the use of the term "hemichannel" be discontinued within the pannexin literature.
authors.affiliation: National Center for Microscopy and Imaging Research, University of California, San Diego, La Jolla, CA, USA. gsosinsky@ucsd.edu
authors.forename: Gina E
authors.initials: GE
authors.lastname: Sosinsky
authors.forename: Daniela
authors.initials: D
authors.lastname: Boassa
authors.forename: Rolf
authors.initials: R
authors.lastname: Dermietzel
authors.forename: Heather S
authors.initials: HS
authors.lastname: Duffy
authors.forename: Dale W
authors.initials: DW
authors.lastname: Laird
authors.forename: Brian
authors.initials: B
authors.lastname: MacVicar
authors.forename: Christian C
authors.initials: CC
authors.lastname: Naus
authors.forename: Silvia
authors.initials: S
authors.lastname: Penuela
authors.forename: Eliana
authors.initials: E
authors.lastname: Scemes
authors.forename: David C
authors.initials: DC
authors.lastname: Spray
authors.forename: Roger J
authors.initials: RJ
authors.lastname: Thompson
authors.forename: Hong-Bo
authors.initials: HB
authors.lastname: Zhao
authors.forename: Gerhard
authors.initials: G
authors.lastname: Dahl
mesh_terms: D000818:Animals; D017630:Connexins / Q000235:genetics / Q000378:metabolism*; D017629:Gap Junctions / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007473:Ion Channels / Q000235:genetics / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D010506:Periodicals as Topic; D055503:Protein Multimerization / Q000502:physiology*; D009626:Terminology as Topic
chemical_list: D017630:Connexins; D007473:Ion Channels; D009419:Nerve Tissue Proteins; C492764:PANX1 protein, human; C492765:PANX2 protein, human; C492766:PANX3 protein, human