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Biochem J. 2002 Aug 1;365(Pt 3):693-9.

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.

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  • 1Department of Medical Biochemistry, University of Wales College of Medicine, Heath Park, Cardiff CF14 4XN, Wales, U.K.

Abstract

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.

PMID:
11985493
[PubMed - indexed for MEDLINE]
PMCID:
PMC1222727
Free PMC Article
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