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

J. Biol. Chem., Vol. 279, Issue 24, 24976-24985, June 11, 2004

This Article Full Text Full Text (PDF) All Versions of this Article: 279/24/24976    most recent M402435200v1 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 Parathath, S. Articles by Connelly, M. A. Search for Related Content PubMed PubMed Citation Articles by Parathath, S. Articles by Connelly, M. A. Social Bookmarking                      What's this?

Glycine 420 Near the C-terminal Transmembrane Domain of SR-BI Is Critical for Proper Delivery and Metabolism of High Density Lipoprotein Cholesteryl Ester^*

Saj Parathath, Daisy Sahoo, Yolanda F. Darlington, Yinan Peng, Heidi L. Collins, George H. Rothblat, David L. Williams, and Margery A. Connelly¶

From the Department of Pharmacological Sciences, University Medical Center, State University of New York, Stony Brook, New York 11794-8651 and the Division of Gastroenterology and Nutrition, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania 19104

Scavenger receptor BI, SR-BI, is a physiologically relevant receptor for high density lipoprotein (HDL) that mediates the uptake of cholesteryl esters and delivers them to a metabolically active membrane pool where they are subsequently hydrolyzed. A previously characterized SR-BI mutant, A-VI, with an epitope tag inserted into the extracellular domain near the C-terminal transmembrane segment, revealed a separation-of-function between SR-BI-mediated HDL cholesteryl ester uptake and cholesterol efflux to HDL, on one hand, and cholesterol release to small unilamellar phospholipid vesicle acceptors and an increased cholesterol oxidase-sensitive pool of membrane free cholesterol on the other. To further elucidate amino acid residues responsible for this separation-of-function phenotype, we engineered alanine substitutions and point mutations in and around the site of epitope tag insertion, and tested these for various cholesterol transport functions. We found that changing amino acid 420 from glycine to histidine had a profound effect on SR-BI function. Despite the ability to mediate selective HDL cholesteryl ester uptake, the G420H receptor had a greatly reduced ability to: 1) enlarge the cholesterol oxidase-sensitive pool of membrane free cholesterol, 2) mediate cholesterol efflux to HDL, even at low concentrations of HDL acceptor where binding-dependent cholesterol efflux predominates, and 3) accumulate cholesterol mass within the cell. Most importantly, the G420H mutant was unable to deliver the HDL cholesteryl ester to a metabolically active membrane compartment for efficient hydrolysis. These observations have important implications regarding SR-BI function as related to its structure near the C-terminal transmembrane domain.

Received for publication, March 3, 2004 , and in revised form, March 26, 2004.

^* This work was supported by National Institutes of Health Grants HL63768, HL58012, and HL22633 and an Atorvastatin Research Award (to M. A. C.) sponsored by Pfizer, Inc. 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.

^¶ To whom correspondence should be addressed: Dept. of Pharmacological Sciences, University Medical Center, State University of New York, Stony Brook, NY 11794-8651. Tel.: 631-444-3078; Fax: 631-444-3218; E-mail: connelly{at}pharm.sunysb.edu.

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

This article has been cited by other articles:

				S. Parathath, Y. F. Darlington, M. de la Llera Moya, D. Drazul-Schrader, D. L. Williams, M. C. Phillips, G. H. Rothblat, and M. A. Connelly Effects of amino acid substitutions at glycine 420 on SR-BI cholesterol transport function J. Lipid Res., June 1, 2007; 48(6): 1386 - 1395. [Abstract] [Full Text] [PDF]