The activation of Cdk5 by p35 plays a pivotal role in a multitude of nervous system activities ranging from neuronal differentiation to degeneration. A fraction of Cdk5 and p35 localizes in the nucleus where Cdk5-p35 exerts its functions via protein phosphorylation, and p35 displays a dynamic localization between the cytoplasm and the nucleus. Here, we examined the nuclear import properties of p35. In nuclear import assays, p35 was actively transported into the nuclei of digitonin-permeabilized HeLa cells and cortical neurons by cytoplasmic carrier-mediated mechanisms. Importin-â, importin-5, and importin-7 were identified to import p35 into the nuclei via a direct interaction with it. An N-terminal region of p35 was defined to interact with the above importins, serving as a nuclear localization signal. Finally, we show that the nuclear localization of p35 does not require the association of Cdk5. Furthermore, Cdk5 and importin-â/5/7 are mutually exclusive in binding to p35. These results suggest that p35 employs pathways distinct from that used by Cdk5 for transport to the nucleus.

Item Type:	Refereed Article
Research Division:	Medical and Health Sciences
Research Group:	Neurosciences
Research Field:	Cellular Nervous System
Objective Division:	Health
Objective Group:	Clinical Health (Organs, Diseases and Abnormal Conditions)
Objective Field:	Nervous System and Disorders
Author:	Cheung, NS (Dr Nam Cheung)
ID Code:	61624
Year Published:	2006
Web of Science® Times Cited:	38
Deposited By:	Menzies Institute for Medical Research
Deposited On:	2010-03-04
Last Modified:	2010-05-04
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