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Blood, 1 September 2008, Vol. 112, No. 5, pp. 2055-2061. Prepublished online as a Blood First Edition Paper on June 17, 2008; DOI 10.1182/blood-2008-04-150276. This Article Full Text (PDF) Supplemental Methods and Figures All Versions of this Article: blood-2008-04-150276v1 112/5/2055    most recent Alert me when this article is cited Alert me if a correction is posted 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 Rights and Permissions Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Lasry, I. Articles by Assaraf, Y. G Search for Related Content PubMed PubMed Citation Articles by Lasry, I. Articles by Assaraf, Y. G Social Bookmarking                   What's this?  Previous Article  |  Next Article  Submitted April 8, 2008 Accepted June 4, 2008 A novel loss of function mutation in the proton-coupled folate transporter from a patient with hereditary folate malabsorption reveals that Arg 113 is crucial for function Inbal Lasry, Bluma Berman, Rachel Straussberg, Yael Sofer, Hanna Bessler, Mohamad Sharkia, Fabian Glaser, Gerrit Jansen, Stavit Drori, and Yehuda G Assaraf* The Fred Wyszkowski Cancer Research Laboratory, Dept. of Biology, Technion-Israel Institute of Technology, Haifa, Israel Dept. of Child Neurology, Schneider Children's Medical Center of Israel, Petach Tikva, Israel Dept. of Medicine, C. Sheba Medical Center, Tel-Hashomer, Israel Laboratory for Immunology and Hematology Research, Rabin Medical Center, Hasharon Hospital, Petach Tikva, Israel General Health Services, Pediatric Primary Care, Jatt, Israel Bioinformatics Knowledge Unit, The Lorry I Lokey Interdisciplinary Center for Life Sciences and Engineering, Technion, Haifa, Israel Dept. of Rheumatology, VU University Medical Center, Amsterdam, Netherlands * Corresponding author; email: assaraf{at}tx.technion.ac.il. Hereditary folate malabsorption (HFM) patients harbor inactivating mutations including R113S in the proton-coupled folate transporter (PCFT), an intestinal folate transporter with optimal activity at acidic pH. Here we identified and characterized a novel R113C mutation residing in the highly conserved first intracellular loop of PCFT. Stable transfectants overexpressing a Myc-tagged wild type (wt)- and mutant R113C PCFT displayed similar transporter targeting to the plasma membrane. However, whereas wt PCFT transfectants showed a 22-fold increase in [3H]folic acid influx at pH 5.5, R113C or mock transfectants showed no increase. Moreover, wt PCFT transfectants displayed a 50% folic acid growth requirement concentration of 7 nM, whereas mock- and R113C transfectants revealed 24-27-fold higher values. Consistently, upon fluorescein-methotrexate labeling, wt PCFT transfectants displayed a 50% methotrexate displacement concentration of 50 nM whereas mock- and R113C transfectants exhibited 12-14-fold higher values. Based upon the crystal structure of the homologous E. coli glycerol-3-phosphate transporter we propose that the cationic R113 residue of PCFT is embedded in a hydrophobic pocket formed by several transmembrane helices which may be part of a folate translocation pore. These findings establish a novel loss of function mutation in HFM residing in an intracellular loop of PCFT crucial for folate transport. CiteULike    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this? This article has been cited by other articles: E. S. Unal, R. Zhao, M.-H. Chang, A. Fiser, M. F. Romero, and I. D. Goldman The Functional Roles of the His247 and His281 Residues in Folate and Proton Translocation Mediated by the Human Proton-coupled Folate Transporter SLC46A1 J. Biol. Chem., June 26, 2009; 284(26): 17846 - 17857. [Abstract] [Full Text] [PDF] R. Zhao, S. H. Min, Y. Wang, E. Campanella, P. S. Low, and I. D. Goldman A Role for the Proton-coupled Folate Transporter (PCFT-SLC46A1) in Folate Receptor-mediated Endocytosis J. Biol. Chem., February 13, 2009; 284(7): 4267 - 4274. [Abstract] [Full Text] [PDF]

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