MOLECULAR BASIS OF CELL AND DEVELOPMENTAL BIOLOGY
The Carboxyl Terminus of Zona Occludens-3 Binds and Recruits a Mammalian Homologue of Discs Lost to Tight Junctions*

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Mammalian homologues of theDrosophila polarity proteins Stardust, Discs Lost, and Crumbs have been identified as Pals1,Pals1-associated tightjunction 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 6thand 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.

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Published, JBC Papers in Press, May 20, 2002, DOI 10.1074/jbc.M201177200

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This work was supported in part by NIDDK, National Institutes of Health Grant DK58208.The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

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Supported by the Medical Scientist Training Program Grant T32 GM07863 and Predoctoral Genetics Training Program Grant T32 GM07544-24 to the University of Michigan during the course of these studies.