Article
- The EMBO Journal (2005) 24, 942 - 951
- doi:10.1038/sj.emboj.7600587
Published online: 17 February 2005
Subject Categories:
Importin 
transports CaMKIV to the nucleus without utilizing importin 
Ippei Kotera1, Toshihiro Sekimoto1, Yoichi Miyamoto2, Takuya Saiwaki1, Emi Nagoshi1, Hiroyuki Sakagami3, Hisatake Kondo3 and Yoshihiro Yoneda1,2
- Department of Cell Biology and Neuroscience, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan
- Department of Frontier Biosciences, Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, Japan
- Department of Cell Biology, Graduate School of Medicine, Tohoku University, Aoba-ku, Sendai, Japan
Correspondence to:
Yoshihiro Yoneda, Department of Frontier Biosciences, Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamada-oka, Suita, Osaka 565-0871, Japan. Tel.: +81 6 6879 4606; Fax: +81 6 6879 4609; E-mail: yyoneda@anat3.med.osaka-u.ac.jp
Received 22 November 2004; Accepted 27 January 2005
Abstract
Ca2+/calmodulin-dependent protein kinase type IV (CaMKIV) plays an essential role in the transcriptional activation of cAMP response element-binding protein-mediated signaling pathways. Although CaMKIV is localized predominantly in the nucleus, the molecular mechanism of the nuclear import of CaMKIV has not been elucidated. We report here that importin 
is able to carry CaMKIV into the nucleus without the need for importin 
or any other soluble proteins in digitonin-permeabilized cells. An importin binding-deficient mutant (
IBB) of importin also carried CaMKIV into the nucleus, which strongly suggests that CaMKIV is transported in an importin -independent manner. While CaMKIV directly interacted with the C-terminal region of importin , the CaMKIV/importin complex did not form a ternary complex with importin , which explains the nonrequirement of importin for the nuclear transport of CaMKIV. The cytoplasmic microinjection of importin -IBB enhanced the rate of nuclear translocation of CaMKIV in vivo. This is the first report to demonstrate definitely that mammalian importin solely carries a cargo protein into the nucleus without utilizing the classical importin -dependent transport system.
Keywords:
- CaMKIV,
- importin ,
- importin ,
- nuclear transport,
- Ran
MORE ARTICLES LIKE THIS
These links to content published by NPG are automatically generated
REVIEWS
MicroRNAs: key players in the immune system, differentiation, tumorigenesis and cell death
Oncogene Review
NEWS AND VIEWS
Nature Structural & Molecular Biology News and Views (01 Oct 2009)
Nature Cell Biology News and Views (01 Jul 1999)
RESEARCH
Importin α can migrate into the nucleus in an importin β- and Ran-independent manner
The EMBO Journal Article (01 Nov 2002)
Snurportin1, an m 3 G-cap-specific nuclear import receptor with a novel domain structure
The EMBO Journal Article (15 Jul 1998)
