HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

J. Biol. Chem., Vol. 278, Issue 23, 21146-21154, June 6, 2003

This Article Full Text Full Text (PDF) Data Supplement All Versions of this Article: 278/23/21146    most recent M300888200v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Valgardsdottir, R. Articles by Prydz, H. Search for Related Content PubMed PubMed Citation Articles by Valgardsdottir, R. Articles by Prydz, H. Social Bookmarking                      What's this?

Transport Signals and Transcription-dependent Nuclear Localization of the Putative DEAD-box Helicase MDDX28^*,

Rut Valgardsdottir  and Hans Prydz 

From the Biotechnology Centre of Oslo, University of Oslo, Gaustadalleen 21, N0349 Oslo, Norway

The human protein MDDX28 is a putative RNA helicase and a nucleocytoplasmic shuttling protein also localized to the mitochondria. Its localization is novel among RNA helicases. We have studied its intracellular targeting signals and show that the first 20 amino acids of MDDX28 are necessary and sufficient for both mitochondrial import and nuclear export of the protein. Mutation of the five leucines in the sequence to alanines abolished the mitochondrial targeting signal as well as greatly reducing the nuclear export signal, indicating that these signal sequences are highly overlapping. Two short stretches of basic amino acids separated by 44 residues were both necessary and sufficient for full nuclear localization. However, they were not absolutely essential, because the protein was present in 7% of the nuclei when both signals were mutated. This indicates that MDDX28 contains another unidentified weak nuclear localization signal(s). Three basic domains in the N-terminal half of the protein and its RNA binding ability were essential for nucleolar localization as well as transcription-inhibition-dependent localization to nuclear subcompartments. Two of these basic domains were the same as those constituting the nuclear localization signal, suggesting that they are responsible for bringing the protein into the nucleus to the sites of RNA binding. Our results indicate that MDDX28 nucleo-cytoplasmic shuttling is dependent on the availability of nascent RNA.

Received for publication, January 27, 2003 , and in revised form, March 18, 2003.

^* This work was supported by grants from the Research Council of Norway, the Norwegian Cancer Society, and the Jahre Foundation (to H. P.). The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

The on-line version of this article (available at http://www.jbc.org) contains a video.

A Research Fellow of the Norwegian Cancer Society.

To whom correspondence should be addressed. Tel.: 47-22840532; Fax: 47-22840501; E-mail: hans.prydz{at}biotek.uio.no.

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				P. Linder Dead-box proteins: a family affair--active and passive players in RNP-remodeling Nucleic Acids Res., September 10, 2006; 34(15): 4168 - 4180. [Abstract] [Full Text] [PDF]