title: The carboxyl terminus of zona occludens-3 binds and recruits a mammalian homologue of discs lost to tight junctions.
abstract: Mammalian homologues of the Drosophila polarity proteins Stardust, Discs Lost, and Crumbs have been identified as Pals1, Pals1-associated tight junction protein (PATJ), and human Crumbs homologue 1 (CRB1), respectively. We have previously demonstrated that PATJ, Pals1, and CRB1 can form a tripartite tight junction complex in epithelial cells and that PATJ recruits Pals1 to tight junctions. Here, we observed that the Pals1/PATJ interaction was not crucial for the ultimate targeting of PATJ itself to tight junctions. This prompted us to examine if any of the 10 post-synaptic density-95/Discs Large/zona occludens-1 (PDZ) domains of PATJ could bind to the carboxyl termini of known tight junction constituents. We found that the 6th and 8th PDZ domains of PATJ can interact with the carboxyl termini of zona occludens-3 (ZO-3) and claudin 1, respectively. PATJ missing the 6th PDZ domain was found to mislocalize away from cell contacts. Surprisingly, deleting the 8th PDZ domain had little effect on PATJ localization. Finally, reciprocal co-immunoprecipitation experiments revealed that full-length ZO-3 can associate with PATJ. Hence, the PATJ/ZO-3 interaction is likely important for recruiting PATJ and its associated proteins to tight junctions.
authors.affiliation: Department of Biological Chemistry, Howard Hughes Medical Institute, University of Michigan Medical School, 1150 W Medical Center Drive, Ann Arbor, MI 48109, USA.
authors.forename: Michael H
authors.initials: MH
authors.lastname: Roh
authors.forename: Chia-Jen
authors.initials: CJ
authors.lastname: Liu
authors.forename: Stephanie
authors.initials: S
authors.lastname: Laurinec
authors.forename: Ben
authors.initials: B
authors.lastname: Margolis
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002352:Carrier Proteins / Q000737:chemistry*; D002460:Cell Line; D003001:Cloning, Molecular; D004247:DNA / Q000378:metabolism; D004285:Dogs; D004847:Epithelial Cells / Q000378:metabolism; D005136:Eye Proteins; D017353:Gene Deletion; D005982:Glutathione Transferase / Q000378:metabolism; D006801:Humans; D015151:Immunoblotting; D008024:Ligands; D008565:Membrane Proteins / Q000737:chemistry*; D018613:Microscopy, Confocal; D008954:Models, Biological; D008969:Molecular Sequence Data; D011233:Precipitin Tests; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D062725:Tight Junction Proteins; D019108:Tight Junctions / Q000378:metabolism*; D014162:Transfection; D062825:Zonula Occludens Proteins
chemical_list: D002352:Carrier Proteins; D005136:Eye Proteins; D008024:Ligands; D008565:Membrane Proteins; C107903:PATJ protein, human; C111873:TJP3 protein, human; D062725:Tight Junction Proteins; D062825:Zonula Occludens Proteins; D004247:DNA; D005982:Glutathione Transferase