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Cysteine is not a substrate but a specific modulator of human ASCT2 (SLC1A5) transporter
Author(s) -
Scalise Mariafrancesca,
Pochini Lorena,
Pingitore Piero,
Hedfalk Kristina,
Indiveri Cesare
Publication year - 2015
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2015.10.011
Subject(s) - cysteine , transporter , chemistry , antiporter , pichia pastoris , efflux , amino acid , substrate (aquarium) , alanine , intracellular , serine , biochemistry , recombinant dna , biophysics , biology , enzyme , membrane , gene , ecology
The Alanine Serine Cysteine Transporter 2 (ASCT2) is involved in balancing the intracellular amino acid pool. This function is allowed by the antiport mechanism and the asymmetric specificity towards different neutral amino acids, distinctive of this transporter. In the present work, the interaction of the putative substrate Cys with the human ASCT2 has been studied using the recombinant hASCT2 over‐produced in Pichia pastoris and the native ASCT2 extracted from HeLa in both proteoliposomes and intact cells. It was found that Cys is a potent competitive inhibitor of hASCT2 but is not a substrate. Moreover, Cys binding to a second site, different from that of substrate, triggers a protein‐mediated unidirectional Gln efflux.