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

J. Biol. Chem., Vol. 282, Issue 3, 2081-2090, January 19, 2007

This Article Full Text Full Text (PDF) Supplemental Data All Versions of this Article: 282/3/2081    most recent M608315200v1 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 HighWire Citing Articles via Google Scholar Google Scholar Articles by Moise, A. R. Articles by Palczewski, K. Search for Related Content PubMed PubMed Citation Articles by Moise, A. R. Articles by Palczewski, K. Social Bookmarking                      What's this?

Topology and Membrane Association of Lecithin: Retinol Acyltransferase^*

From the Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106-4965

Fatty acid retinyl esters are the storage form of vitamin A (all-trans-retinol) and serve as metabolic intermediates in the formation of the visual chromophore 11-cis-retinal. Lecithin:retinol acyltransferase (LRAT), the main enzyme responsible for retinyl ester formation, acts by transferring an acyl group from the sn-1 position of phosphatidylcholine to retinol. To define the membrane association and localization of LRAT, we produced an LRAT-specific monoclonal antibody, which we used to study enzyme partition under different experimental conditions. Furthermore, we examined the membrane topology of LRAT through an N-linked glycosylation scanning approach and protease protection assays. We show that LRAT is localized to the membrane of the endoplasmic reticulum (ER) and assumes a single membrane-spanning topology with an N-terminal cytoplasmic/C-terminal luminal orientation. In eukaryotic cells, the C-terminal transmembrane domain is essential for the activity and ER membrane targeting of LRAT. In contrast, the N-terminal hydrophobic region is not required for ER membrane targeting or enzymatic activity, and its amino acid sequence is not conserved in other species examined. We present experimental evidence of the topology and subcellular localization of LRAT, a critical enzyme in vitamin A metabolism.

Received for publication, August 31, 2006 , and in revised form, November 15, 2006.

^* This work was supported in part by NEI Grant EY009339 from the National Institutes of Health (to K. 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 supplemental Fig. 1.

¹ To whom correspondence may be addressed: Dept. of Pharmacology, School of Medicine, Case Western Reserve University, Biomedical Research Bldg., 10900 Euclid Ave., Cleveland, OH 44106-4965. Tel.: 216-368-1284; Fax: 216-368-1300; E-mail: ram50{at}case.edu.

² To whom correspondence may be addressed: Dept. of Pharmacology, School of Medicine, Case Western Reserve University, Biomedical Research Bldg., 10900 Euclid Ave., Cleveland, OH 44106-4965. Tel.: 216-368-4631; Fax: 216-368-1300; E-mail: kxp65{at}case.edu.

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

This article has been cited by other articles:

				L. P. Wright, H. Court, A. Mor, I. M. Ahearn, P. J. Casey, and M. R. Philips Topology of Mammalian Isoprenylcysteine Carboxyl Methyltransferase Determined in Live Cells with a Fluorescent Probe Mol. Cell. Biol., April 1, 2009; 29(7): 1826 - 1833. [Abstract] [Full Text] [PDF]

				Y. Imanishi, W. Sun, T. Maeda, A. Maeda, and K. Palczewski Retinyl Ester Homeostasis in the Adipose Differentiation-related Protein-deficient Retina J. Biol. Chem., September 5, 2008; 283(36): 25091 - 25102. [Abstract] [Full Text] [PDF]

				R. A. Radu, J. Hu, J. Peng, D. Bok, N. L. Mata, and G. H. Travis Retinal Pigment Epithelium-Retinal G Protein Receptor-Opsin Mediates Light-dependent Translocation of All-trans-retinyl Esters for Synthesis of Visual Chromophore in Retinal Pigment Epithelial Cells J. Biol. Chem., July 11, 2008; 283(28): 19730 - 19738. [Abstract] [Full Text] [PDF]