title: Connexin45 directly binds to ZO-1 and localizes to the tight junction region in epithelial MDCK cells.
abstract: Zonula occludens protein 1 (ZO-1) is a cytosolic tight junction protein that tethers transmembrane proteins such as occludin, claudin and junctional adhesion molecule to the actin cytoskeleton. The interaction between ZO-1 and claudin or junctional adhesion molecule occurs via the amino-terminal PSD95/Dlg/ZO-1 (PDZ) domains in ZO-1. A yeast two-hybrid screen to search for proteins that interact with the PDZ domains of ZO-1 identified connexin (Cx) 45. Cx45 interacts with the PDZ domains of ZO-1 and ZO-3, but not ZO-2, via a short C-terminal PDZ binding motif (SVWI). In transfected epithelial Madin-Darby canine kidney cells, Cx45 co-localizes with endogenous ZO-1 at or near tight junctions and co-precipitation experiments show that Cx45 and ZO-1 directly interact. Inactivating the C-terminal PDZ-binding motif in Cx45 affects its co-precipitation and co-localization with ZO-1. The growing number of connexins (i.e. Cx43 and Cx45) that can associate with ZO proteins indicate that ZO proteins may play a more general role in organizing gap junctions and/or in recruiting signaling molecules that regulate intercellular communication.
authors.affiliation: Institute of Molecular and Cell Biology, Epithelial Cell Biology Laboratory, Singapore.
authors.forename: P J
authors.initials: PJ
authors.lastname: Kausalya
authors.forename: M
authors.initials: M
authors.lastname: Reichert
authors.forename: W
authors.initials: W
authors.lastname: Hunziker
mesh_terms: D000818:Animals; D001665:Binding Sites; D002352:Carrier Proteins / Q000378:metabolism; D016764:Cell Polarity; D002478:Cells, Cultured; D017630:Connexins / Q000235:genetics / Q000378:metabolism*; D004285:Dogs; D004847:Epithelial Cells / Q000378:metabolism; D017629:Gap Junctions / Q000378:metabolism*; D007668:Kidney / Q000166:cytology / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D009154:Mutation; D010750:Phosphoproteins / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D014162:Transfection; D020798:Two-Hybrid System Techniques; D062825:Zonula Occludens Proteins; D062826:Zonula Occludens-1 Protein; D062827:Zonula Occludens-2 Protein
chemical_list: D002352:Carrier Proteins; D017630:Connexins; D008565:Membrane Proteins; D010750:Phosphoproteins; C569043:Tjp1 protein, mouse; C569047:Tjp2 protein, mouse; C491774:Tjp3 protein, mouse; D062825:Zonula Occludens Proteins; D062826:Zonula Occludens-1 Protein; D062827:Zonula Occludens-2 Protein; C082920:connexin 45