Premium
Roles of immunoglobulin‐like loops of junctional cell adhesion molecule 4; involvement in the subcellular localization and the cell adhesion
Author(s) -
Tajima Makiko,
Hirabayashi Susumu,
Yao Ikuko,
Shirasawa Madoka,
Osuga Junichi,
Ishibashi Shun,
Fujita Toshiro,
Hata Yutaka
Publication year - 2003
Publication title -
genes to cells
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.912
H-Index - 115
eISSN - 1365-2443
pISSN - 1356-9597
DOI - 10.1046/j.1365-2443.2003.00673.x
Subject(s) - microbiology and biotechnology , subcellular localization , biology , tight junction , immunoglobulin superfamily , guanylate kinase , cell adhesion molecule , pdz domain , adhesion , cell adhesion , antibody , membrane , membrane protein , cell , chemistry , immunology , biochemistry , cytoplasm , organic chemistry
Background: Membrane‐associated guanylate kinase with inverted domain structure‐1 (MAGI‐1) is a scaffolding protein at tight junctions (TJs). We have recently identified junctional adhesion molecule 4 (JAM4) as a MAGI‐1‐interacting protein. JAM4 belongs to the immunoglobulin superfamily and mediates Ca 2+ ‐independent adhesion. In this study, we examined the subcellular localization of JAM4 in various tissues and the involvement of JAM4 in the localization of MAGI‐1. Moreover, we investigated into roles of immunoglobulin‐like loops (Ig‐loops) of JAM4. Results: JAM4 was localized at TJs but also on apical membranes of epithelial cells in jejunum, ileum, and renal proximal tubules. In Madine Darby canine kidney (MDCK) cells, the localization of JAM4 at TJs depended on the first Ig‐loop and did not require the MAGI‐1‐interacting region. JAM4 determined the subcellular localization of MAGI‐1 in MDCK cells. In ileum, however, MAGI‐1 was localized at TJs where JAM4 was not detected. Both of Ig‐loops were necessary for homophilic interactions, but cis interactions depended on the first Ig‐loop. Conclusion: JAM4 may be primarily targeted to apical membranes, and subsequently recruited to TJs through the first Ig‐loop–mediated molecular interaction. JAM4 determines the localization of MAGI‐1 in MDCK cells, but the in vivo localization of MAGI‐1 does not necessarily depend on JAM4.