Gap junctions are specialized cell–cell contacts that provide direct intercellular communication between eukaryotic cells. The tyrosine-sorting signal (YXXØ), present at amino acids 286–289 of Cx43 (connexin43), has been implicated in the internalization of the protein. In recent years, ubiquitination of Cx43 has also been proposed to regulate gap junction intercellular communication; however, the underlying mechanism and molecular players involved remain elusive. In the present study, we demonstrate that ubiquitinated Cx43 is internalized through a mechanism that is independent of the YXXØ signal. Indeed, expression of a Cx43–Ub (ubiquitin) chimaera was shown to drive the internalization of a mutant Cx43 in which the YXXØ motif was eliminated. Immunofluorescence, cycloheximide-chase and cell-surface-protein biotinylation experiments demonstrate that oligomerization of Cx43–Ub into hemichannels containing wild-type Cx43 or mutant Cx43Y286A is sufficient to drive the internalization of the protein. Furthermore, the internalization of Cx43 induced by Cx43–Ub was shown to depend on its interaction with epidermal growth factor receptor substrate 15.
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Research Article|
June 28 2011
Ubiquitin-mediated internalization of connexin43 is independent of the canonical endocytic tyrosine-sorting signal
Steve Catarino;
Steve Catarino
1Centre of Ophthalmology and Vision Sciences, Biomedical Institute for Research in Light and Image (IBILI), Faculty of Medicine, University of Coimbra, Azinhaga de Sta Comba, 3000-354 Coimbra, Portugal
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José S. Ramalho;
José S. Ramalho
1Centre of Ophthalmology and Vision Sciences, Biomedical Institute for Research in Light and Image (IBILI), Faculty of Medicine, University of Coimbra, Azinhaga de Sta Comba, 3000-354 Coimbra, Portugal
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Carla Marques;
Carla Marques
1Centre of Ophthalmology and Vision Sciences, Biomedical Institute for Research in Light and Image (IBILI), Faculty of Medicine, University of Coimbra, Azinhaga de Sta Comba, 3000-354 Coimbra, Portugal
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Paulo Pereira;
Paulo Pereira
1Centre of Ophthalmology and Vision Sciences, Biomedical Institute for Research in Light and Image (IBILI), Faculty of Medicine, University of Coimbra, Azinhaga de Sta Comba, 3000-354 Coimbra, Portugal
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Henrique Girão
Henrique Girão
1
1Centre of Ophthalmology and Vision Sciences, Biomedical Institute for Research in Light and Image (IBILI), Faculty of Medicine, University of Coimbra, Azinhaga de Sta Comba, 3000-354 Coimbra, Portugal
1To whom correspondence should be addressed (email hgirao@ibili.uc.pt).
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Publisher: Portland Press Ltd
Received:
December 16 2010
Revision Received:
April 21 2011
Accepted:
May 09 2011
Accepted Manuscript online:
May 09 2011
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© The Authors Journal compilation © 2011 Biochemical Society
2011
Biochem J (2011) 437 (2): 255–267.
Article history
Received:
December 16 2010
Revision Received:
April 21 2011
Accepted:
May 09 2011
Accepted Manuscript online:
May 09 2011
Citation
Steve Catarino, José S. Ramalho, Carla Marques, Paulo Pereira, Henrique Girão; Ubiquitin-mediated internalization of connexin43 is independent of the canonical endocytic tyrosine-sorting signal. Biochem J 15 July 2011; 437 (2): 255–267. doi: https://doi.org/10.1042/BJ20102059
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