Please use this identifier to cite or link to this item:
Title: Thiol modification of cysteine 327 in the eighth transmembrane domain of the light subunit xCT of the heteromeric cystine/glutamate antiporter suggests close proximity to the substrate binding site/permeation pathway
Author: Jiménez Vidal, Maite
Gasol Escuer, Emma
Zorzano Olarte, Antonio
Nunes Martínez, Virginia
Palacín Prieto, Manuel
Chillarón Chaves, José Julio
Keywords: Aminoàcids
Proteïnes portadores
Proteïnes de membrana
Amino acids
Carrier proteins
Membrane proteins
Issue Date: 19-Mar-2004
Publisher: American Society for Biochemistry and Molecular Biology
Abstract: We measured sensitivity to thiol modification of the heteromeric glutamate/cystine transporter 4F2hc-xCT expressed in Xenopus oocytes. p-Chloromercuribenzoate (pCMB) and p-chloromercuribenzenesulfonate (pCMBS) rapidly blocked transport activity. Cys(327), located in the middle of the eighth transmembrane domain of the light subunit (xCT), was found to be the main target of inactivation. Cysteine, an impermeant reducing reagent, reversed pCMB and pCMBS effects only when applied from the extracellular medium. l-Glutamate and l-cystine, but not l-arginine, protected from the inactivation with an IC(50) similar to the K(m). Protection was not temperature-dependent, suggesting that it did not depend on large substrate-induced conformational changes. Mutation of Cys(327) to Ala and Ser slightly modified the K(m) and a C327L mutant abolished transport function without compromising transporter expression at the plasma membrane. The results indicate that Cys(327) is a functionally important residue accessible to the aqueous extracellular environment and is structurally linked to the permeation pathway and/or the substrate binding site.
Note: Reproducció del document publicat a:
It is part of: Journal of Biological Chemistry, 2004, vol. 279, num. 12, p. 11214-11221
Related resource:
ISSN: 0021-9258
Appears in Collections:Articles publicats en revistes (Bioquímica i Biomedicina Molecular)
Articles publicats en revistes (Ciències Fisiològiques)
Articles publicats en revistes (Biologia Cel·lular, Fisiologia i Immunologia)

Files in This Item:
File Description SizeFormat 
538532.pdf431.34 kBAdobe PDFView/Open

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.