xCT cystine transporter expression in HEK293 cells: Pharmacology and localization

xCT, the core subunit of the system x(c)(-), high affinity cystine transpor ter, belongs to a superfamily of glycoprotein-associated amino acid transpo rters. Although xCT was shown to promote cystine transport in,Xenopus oocyt es, little work has been done with mammalian cells (Sato, H.1 Tamba, M., Is hii, T., and Bannai, S. J. Biol. Chem. 274, 11455-11458, 1999). Therefore, me have constructed mammalian expression vectors for murine xCT and its acc essory subunit 4F2hc and transfected them into HEK293 cells. We report that this transporter binds cystine with high affinity (81 muM) and displays a pharmacological profile expected for system x(c)(-). Surprisingly, xCT tran sport activity in HEK293 cells is not, dependent on the coexpression of the essgenous 4F2hc. Expression of GFP-tagged xCT indicated a highly clustered plasma membrane and intracellular distribution suggesting the presence of subcellular domains associated with combating oxidative stress. Our results indicate that HEK293 cells transfected with the xCT subunit mould be a use ful vehicle for future structure-function and pharmacology experiments invo lving system x(c)(-). (C) 2001 Academic Press.