The gap junction protein connexin43 interacts with the second PDZ domain of the zona occludens-1 protein.
Gap junctions mediate cell-cell communication in almost all tissues and are composed of channel-forming integral membrane proteins, termed connexins [1-3]. Connexin43 (Cx43) is the most widely expressed and the most well-studied member of this family. Cx43-based cell-cell communication is regulated by growth factors and oncogenes [3-5], although the underlying mechanisms are poorly understood as cellular proteins that interact with connexins have yet to be identified. The carboxy-terminal cytosolic domain of Cx43 contains several phosphorylation sites and potential signalling motifs. We have used a yeast two-hybrid protein interaction screen to identify proteins that bind to the carboxy-terminal tail of Cx43 and thereby isolated the zona occludens-1 (ZO-1) protein. ZO-1 is a 220 kDa peripheral membrane protein containing multiple protein interaction domains including three PDZ domains and a Src homology 3 (SH3) domain [6-9]. The interaction of Cx43 with ZO-1 occurred through the extreme carboxyl terminus of Cx43 and the second PDZ domain of ZO-1. Cx43 associated with ZO-1 in Cx43-transfected COS7 cells, as well as endogenously in normal Rat-1 fibroblasts and mink lung epithelial cells. Confocal microscopy revealed that endogenous Cx43 and ZO-1 colocalised at gap junctions. We suggest that ZO-1 serves to recruit signalling proteins into Cx43-based gap junctions.
Division of Cellular Biochemistry The Netherlands Cancer Institute Plesmanlaan 121, 1066 CX, Amsterdam, The Netherlands.
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D000818:Animals; D001665:Binding Sites; D002450:Cell Communication; D002478:Cells, Cultured; D003001:Cloning, Molecular; D018031:Connexin 43 / Q000737:chemistry / Q000378:metabolism*; D017931:DNA Primers; D017629:Gap Junctions / Q000502:physiology*; D006801:Humans; D008297:Male; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D010750:Phosphoproteins / Q000737:chemistry / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D051381:Rats; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D012441:Saccharomyces cerevisiae; D013737:Testis / Q000378:metabolism; D014162:Transfection; D062826:Zonula Occludens-1 Protein
D018031:Connexin 43; D017931:DNA Primers; D008565:Membrane Proteins; D010750:Phosphoproteins; D011994:Recombinant Proteins; C569042:TJP1 protein, human; C569044:Tjp1 protein, rat; D062826:Zonula Occludens-1 Protein