Contactin-associated protein (Caspr) 2 interacts with carboxypeptidase E in the CNS |
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Authors: | Shigeru Oiso Yasuo Takeda Toshitaka Futagawa Takehiko Miura Satoshi Kuchiiwa† Kentaro Nishida Ryuji Ikeda Hiroko Kariyazono‡ Kazutada Watanabe§ Katsushi Yamada |
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Institution: | Department of Clinical Pharmacy and Pharmacology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan; Department of Neuroanatomy, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan; Department of Pharmacy, Faculty of Pharmaceutical Sciences, Nagasaki International University, Nagasaki, Japan; Department of BioEngineering, Nagaoka University of Technology, Nagaoka, Niigata, Japan |
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Abstract: | To identify proteins interacting with the intracellular domain of the neural cell adhesion molecule contactin-associated protein 2 (Caspr2), yeast two-hybrid screening was performed. We identified carboxypeptidase E (CPE) as a Caspr2-interacting candidate protein. Glutathione S -transferase pull-down and immunoprecipitation analyses indicated that Caspr2 was associated with CPE in vitro and in vivo . Both Caspr2 and CPE were expressed predominantly in the CNS. Immunohistochemical analyses revealed that both Caspr2- and CPE-like immunoreactivities were found to co-localize in the apical dendrites and cell bodies of rat cortical neurons. In subcellular localization analysis, Caspr2- and CPE-like immunoreactivities were co-migrated in the fractions of Golgi/ER. Additionally, in COS-7 cells co-transfected with CPE and Caspr2 cDNAs, Caspr2- and CPE-immunoreactivities were co-localized in both Golgi and membrane, whereas it was only observed in Golgi of either COS-7 cell transfected with CPE or Caspr2 cDNA alone. It is known that the membrane-bound form of CPE functions as a sorting receptor of prohormones in the trans -Golgi network. Taken together, our data suggest that CPE may be a key molecule to regulate Caspr2 trafficking to the cell membrane. |
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Keywords: | apical dendrite Caspr2 CPE Golgi apparatus membrane trafficking yeast two-hybrid |
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