Contactin-associated protein (Caspr) 2 interacts with carboxypeptidase E in the CNS.
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.
Oiso
Shigeru
S
Department of Clinical Pharmacy and Pharmacology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan.
Takeda
Yasuo
Y
Futagawa
Toshitaka
T
Miura
Takehiko
T
Kuchiiwa
Satoshi
S
Nishida
Kentaro
K
Ikeda
Ryuji
R
Kariyazono
Hiroko
H
Watanabe
Kazutada
K
Yamada
Katsushi
K
D000818:Animals; D019556:COS Cells; D043423:Carboxypeptidase H / Q000378:metabolism* / Q000502:physiology; D002490:Central Nervous System / Q000201:enzymology / Q000378:metabolism*; D002540:Cerebral Cortex / Q000201:enzymology / Q000378:metabolism; D002522:Chlorocebus aethiops; D006801:Humans; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism* / Q000502:physiology; D009419:Nerve Tissue Proteins / Q000378:metabolism* / Q000502:physiology; D011485:Protein Binding / Q000502:physiology; D021381:Protein Transport / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar
C403049:CNTNAP2 protein, human; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D043423:Carboxypeptidase H