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

J. Biol. Chem., Vol. 281, Issue 42, 31677-31688, October 20, 2006

This Article Full Text Full Text (PDF) Supplemental data All Versions of this Article: 281/42/31677    most recent M601828200v1 Submit a Letter to Editor Alert me when this article is cited Alert me when eLetters are posted 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 Request Permissions Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Lam-Yuk-Tseung, S. Articles by Gros, P. Search for Related Content PubMed PubMed Citation Articles by Lam-Yuk-Tseung, S. Articles by Gros, P. Social Bookmarking                      What's this?

Identification of a Tyrosine-based Motif (YGSI) in the Amino Terminus of Nramp1 (Slc11a1) That Is Important for Lysosomal Targeting^*

From the Department of Biochemistry, McGill Cancer Center and Center for Host Resistance, McGill University, Montreal, Quebec H3G 1Y6, Canada

In macrophages, Nramp1 (Slc11a1) is expressed in lysosomes and restricts replication of intracellular pathogens by removing divalent metals (Mn²⁺ and Fe²⁺) from the phagolysosome. Nramp2 (DMT1, Slc11a2) is expressed both at the duodenal brush border where it mediates uptake of dietary iron and ubiquitously at the plasma membrane/recycling endosomes of many cell types where it transports transferrin-associated iron across the endosomal membrane. In Nramp2, a carboxyl-terminal cytoplasmic motif (⁵⁵⁵YLLNT⁵⁵⁹) is critical for internalization and recycling of the transporter from the plasma membrane. Here we studied the subcellular trafficking properties of Nramp1 and investigated the cis-acting sequences responsible for targeting to lysosomes. For this, we constructed and studied Nramp1/Nramp2 chimeric proteins where homologous domains of each protein were exchanged. Chimeras exchanging the amino-(upstream TM1) and carboxyl-terminal (downstream TM12) cytoplasmic segments of both transporters were stably expressed in porcine LLC-PK₁ kidney cells and were studied with respect to expression, maturation, stability, cell surface targeting, transport activity, and subcellular localization. An Nramp2 isoform II chimera bearing the amino terminus of Nramp1 was not expressed at the cell surface but was targeted to lysosomes. This lysosomal targeting was abolished by single alanine substitutions at Tyr¹⁵ and Ile¹⁸ of a ¹⁵YGSI¹⁸ motif present in the amino terminus of Nramp1. These results identify YGSI as a tyrosine-based sorting signal responsible for lysosomal targeting of Nramp1.

Received for publication, February 27, 2006 , and in revised form, July 25, 2006.

^* 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 supplemental Table 1 and Figs. 1-3.

¹ To whom correspondence should be addressed: Dept. of Biochemistry, McGill University, 3655 Promenade Sir William Osler, Montreal, Quebec H3G 1Y6, Canada. Tel.: 514-398-7291; Fax: 514-398-2603; E-mail: philippe.gros{at}mcgill.ca.

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