title: Localization of p0071-interacting proteins, plakophilin-related armadillo-repeat protein-interacting protein (PAPIN) and ERBIN, in epithelial cells.
abstract: PAPIN has six PDZ domains and interacts with p0071, a catenin-related protein. Recent studies have revealed that catenins determine the subcellular localization of some PDZ proteins. We have examined whether the localization of PAPIN is determined by p0071 in epithelial cells. PAPIN was localized not only on the lateral membrane but also on the apical membrane, where p0071 was absent. The targeting to both membranes was mediated by the middle region of PAPIN and did not require the p0071-interacting PDZ domain. In cells that came into contact, PAPIN was diffusely distributed on the plasma membrane, while p0071 was concentrated at immature cell-cell contacts. When epithelial cells were exposed to the low concentration of calcium, p0071 was internalized, whereas PAPIN remained on the plasma membrane. We also confirmed that the interaction with p0071 was not essential for the membrane targeting of ERBIN, a recently identified p0071- and ErbB2-binding protein. PAPIN, p0071, and ERBIN formed a complex in 293T cells. Furthermore, ERBIN and ErbB2 were colocalized with PAPIN on the lateral membrane. These findings suggest that PAPIN, p0071, and ERBIN come to the cell-cell contacts independently and interact with each other on the lateral membrane.
authors.affiliation: Department of Medical Biochemistry, Graduate School of Medicine, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8519, Japan.
authors.forename: Hideki
authors.initials: H
authors.lastname: Ohno
authors.forename: Susumu
authors.initials: S
authors.lastname: Hirabayashi
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Iizuka
authors.forename: Hirohide
authors.initials: H
authors.lastname: Ohnishi
authors.forename: Toshiro
authors.initials: T
authors.lastname: Fujita
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Hata
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D001483:Base Sequence; D002352:Carrier Proteins / Q000032:analysis* / Q000378:metabolism; D015815:Cell Adhesion Molecules; D002462:Cell Membrane / Q000737:chemistry; D002478:Cells, Cultured; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D004285:Dogs; D004847:Epithelial Cells / Q000737:chemistry; D007365:Intercellular Junctions / Q000502:physiology; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins; D051191:Plakophilins; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000032:analysis
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D015815:Cell Adhesion Molecules; D003598:Cytoskeletal Proteins; D009363:Neoplasm Proteins; D051191:Plakophilins; D018719:Erb-b2 Receptor Tyrosine Kinases; C413364:ERBIN protein, human; C423943:PDZD2 protein, human; C105677:PKP4 protein, human