Glutamine is taken up into the rat hepatoma cell line H4-IIE-C3 by a Na+-dependent transport system which is specific for glutamine, alanine, serine, cysteine and asparagine and does not tolerate substitution of Na+ by Li+. Glutamine transport was relatively weakly inhibited by a 50-fold excess of leucine and was not inhibited by phenylalanine or N-methyl aminoisobutyrate. These general properties are characteristic of the recently identified ASCT/B0 family of transporters. Using a reverse transcriptase PCR-based homology cloning approach, we have characterized a cDNA for a novel member of this transporter family (H4-ASCT2) from H4-IIE-C3 cells. The cDNA encodes a 551-amino acid protein which exhibits similarities of between 75 and 85% with ASCT/B0 transporters previously cloned from other sources. When expressed in Xenopus oocytes, this transporter catalyses Na+-dependent glutamine uptake with characteristics very similar to those of glutamine uptake into the H4-IIE-C3 cells. This newly characterized transporter possesses a number of amino acid sequence differences from ASCT2 clones recently isolated from rat astroglial cells and from normal rat liver. In particular, the loop region between transmembrane helices 3 and 4 from H4-ASCT2 shares less than 60% sequence similarity with ASCT2 from rat liver; furthermore, there are some 25 single amino acid substitutions elsewhere in the H4-ASCT2 sequence compared with that from rat liver. Thus enhanced glutamine uptake in rat hepatoma cells is mediated by the expression of a novel ASCT/B0 transporter isoform rather than by increased expression of the ASCT2 mRNA found in normal rat liver.
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November 15 2002
Identification of a plasma membrane glutamine transporter from the rat hepatoma cell line H4-IIE-C3 Available to Purchase
Matthew POLLARD;
Matthew POLLARD
∗Department of Biochemistry, School of Medical Sciences, University Walk, Bristol BS8 1TD U.K.,
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David MEREDITH;
David MEREDITH
†Department of Human Anatomy and Genetics, South Parks Road, Oxford OX1 3QX, U.K.
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John D. McGIVAN
John D. McGIVAN
1
∗Department of Biochemistry, School of Medical Sciences, University Walk, Bristol BS8 1TD U.K.,
1To whom correspondence should be addressed (e-mail [email protected]).
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Publisher: Portland Press Ltd
Received:
June 25 2002
Revision Received:
July 29 2002
Accepted:
August 12 2002
Accepted Manuscript online:
August 12 2002
Online ISSN: 1470-8728
Print ISSN: 0264-6021
The Biochemical Society, London ©2002
2002
Biochem J (2002) 368 (1): 371–375.
Article history
Received:
June 25 2002
Revision Received:
July 29 2002
Accepted:
August 12 2002
Accepted Manuscript online:
August 12 2002
Citation
Matthew POLLARD, David MEREDITH, John D. McGIVAN; Identification of a plasma membrane glutamine transporter from the rat hepatoma cell line H4-IIE-C3. Biochem J 15 November 2002; 368 (1): 371–375. doi: https://doi.org/10.1042/bj20020982
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