Gap-junction channels provide a widespread intercellular signalling mechanism. They are constructed of a family of connexin membrane proteins that thread across the membrane four times and oligomerize to generate hexameric gap-junction hemichannels. Using an in vitro cell-free transcription/translation system, we demonstrate that connexin (Cx) 26, one of the smallest connexins, is integrated directly in a post-translational manner into plasma membranes. Protein-cleavage studies of Cx26 integrated into plasma membranes indicate a similar native transmembrane topography to that of Cx26 integrated co-translationally into microsomes. Cx26 integrated post-translationally into plasma membranes oligomerizes and, when incorporated into liposomes, provides permeability to ascorbic acid, suggesting that gap-junction hemichannels are generated. The results provide the basis of a novel alternative mechanism for spontaneous assembly in plasma membranes of Cx26 gap-junction hemichannels that occurs independently of the conventional biogenesis of gap junctions involving connexin trafficking and oligomerization via membrane components of the secretory pathway.
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August 2002
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Research Article|
August 01 2002
Post-translational integration and oligomerization of connexin 26 in plasma membranes and evidence of formation of membrane pores: implications for the assembly of gap junctions
Shoeb AHMAD;
Shoeb AHMAD
1
Department of Medical Biochemistry, University of Wales College of Medicine, Heath Park, Cardiff CF14 4XN, Wales, U.K.
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W. Howard EVANS
W. Howard EVANS
2
Department of Medical Biochemistry, University of Wales College of Medicine, Heath Park, Cardiff CF14 4XN, Wales, U.K.
2To whom correspondence should be addressed (e-mail wmbwhe@cardiff.ac.uk).
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Publisher: Portland Press Ltd
Received:
October 26 2001
Revision Received:
April 26 2002
Accepted:
May 02 2002
Online ISSN: 1470-8728
Print ISSN: 0264-6021
The Biochemical Society, London ©2002
2002
Biochem J (2002) 365 (3): 693–699.
Article history
Received:
October 26 2001
Revision Received:
April 26 2002
Accepted:
May 02 2002
Citation
Shoeb AHMAD, W. Howard EVANS; Post-translational integration and oligomerization of connexin 26 in plasma membranes and evidence of formation of membrane pores: implications for the assembly of gap junctions. Biochem J 1 August 2002; 365 (3): 693–699. doi: https://doi.org/10.1042/bj20011572
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