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First published online August 6, 2008

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Connexins mind the gap

To make a gap junction, cells assemble six plasma-membrane connexin proteins into a hemichannel; in turn, two hemichannels on adjacent cells dock to form a complete intercellular channel. Mutations in the cytoplasmic N-terminal domain of connexins affect the physiological properties of hemichannels and give rise to several inherited diseases, but the molecular basis of these effects has been unclear. Now, Eric Beyer and colleagues (p. 2744) investigate the role of the 23-amino-acid N-terminus of connexin37 (CX37) in hemichannel formation and function. The authors show that N-terminal deletion mutants of CX37 can form gap-junction plaques in transiently transfected HeLa cells, provided that nine or more amino acids are present. By contrast, none of the tested mutants allow the intercellular transfer of neurobiotin, whereas wild-type CX37 does; moreover, the mutants do not form conducting hemichannels in Xenopus oocytes. A full-length CX37 mutant, in which N-terminal residues 2-8 are replaced by alanines, forms plaques but, similar to the deletion mutants, does not restore function. Thus, many N-terminal connexin residues are dispensable for the formation of plaques (and for membrane insertion and trafficking, which precede plaque formation). Instead, the authors conclude, the N-terminus has an essential role in hemichannel gating.

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Related articles in JCS:

An intact connexin N-terminus is required for function but not gap junction formation

John W. Kyle, Peter J. Minogue, Bettina C. Thomas, Denise A. Lopez Domowicz, Viviana M. Berthoud, Dorothy A. Hanck, and Eric C. Beyer
JCS 2008 121: 2744-2750. [Abstract] [Full Text]  

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Related articles in JCS Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Search for Related Content Social Bookmarking                         What's this?