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

This Article Summary Full Text Full Text (PDF) All Versions of this Article: fj.05-5588fjev1 20/13/2390    most recent Alert me when this article is cited Alert me if a correction is posted 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 Google Scholar Google Scholar Articles by Okkenhaug, H. Articles by Sardini, A. Search for Related Content PubMed PubMed Citation Articles by Okkenhaug, H. Articles by Sardini, A.

The human ClC-4 protein, a member of the CLC chloride channel/transporter family, is localized to the endoplasmic reticulum by its N-terminus

Hanneke Okkenhaug^*,1, Karsten-Henrich Weylandt^*,2, David Carmena^*, Dominic J. Wells, Christopher F. Higgins^* and Alessandro Sardini^*,3

^* MRC Clinical Sciences Centre, Faculty of Medicine, Hammersmith Hospital Campus, Imperial College, London, UK; and

Gene Targeting Unit, Department of Cellular and Molecular Neurosciences, Division of Neuroscience and Psychological Medicine, Faculty of Medicine, Charing Cross Campus, Imperial College, London, UK

³Correspondence: MRC Clinical Sciences Centre, Imperial College Faculty of Medicine, Hammersmith Hospital Campus, Du Cane Rd., London W12 0NN, UK. E-mail: a.sardini{at}csc.mrc.ac.uk

ABSTRACT

Despite considerable similarity in their amino acid sequences and structural features, the mammalian members of the CLC chloride channel/transporter family have different subcellular locations. The subcellular location and function of one of these members, hClC-4, is controversial. To characterize its cellular function, we investigated its tissue distribution and subcellular location. Expression was high in excitable tissues such as the nervous system and skeletal muscle. When heterologously expressed in HEK293 cells and in skeletal muscle fibers, hClC-4 localizes to the endoplasmic/sarcoplasmic reticulum (ER/SR) membranes, in contrast to hClC-3, which localizes to vesicular structures. This location was confirmed by identification of endogenous ClC-4 in membrane fractions from mouse brain homogenate enriched for the sarco-endoplasmic reticulum ATPase SERCA2, an ER/SR marker. To identify the motif responsible for ER localization of hClC-4, we generated hClC-4 truncations and chimeras between hClC-4 and hClC-3 or the unrelated plasma membrane protein Ly49E. A stretch of amino acids, residues 14–63, at the N-terminus constitutes a novel motif both necessary and sufficient for targeting hClC-4 and other membrane proteins to the ER.—Okkenhaug, H., Weylandt, K.-H., Carmena, D., Wells, D. J., Higgins, C. F., Sardini, A. The human ClC-4 protein, a member of the CLC chloride channel/transporter family, is localized to the endoplasmic reticulum by its N-terminus.