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Hydrophobic residues and amino terminal phosphorylation site are essential for urate/urate exchange mediated by human glucose transporter 9, hSLC2A9 (908.10)
Author(s) -
Long Wentong,
Witkowska Kate,
O'Neill Debbie,
Wong Kenneth,
Cheeseman Chris
Publication year - 2014
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.28.1_supplement.908.10
Subject(s) - chemistry , biochemistry , mutant , phosphorylation , serine , transporter , efflux , uric acid , glucose transporter , biology , endocrinology , gene , insulin
Human urate homeostasis is achieved primarily in liver and kidney, where urate is significantly regulated by human SLC2A9a and 9b. These transporters show trans‐acceleration between urate and hexoses, and urate/urate; however, the mechanism has not been identified.Our preliminary data suggested that phosphorylation of hSLC2A9 is an important process for urate transport regulation and serine 9 has been postulated to be an important phosphorylation site in the N‐terminus of 9a. Objective:To investigate urate/urate trans‐acceleration mechanism mediated by9a,9b and their mutants. Methods: hSLC2A9 isoforms and mutants were over expressed in X. laevis oocytes. Urate/urate trans‐stimulation activities were determined by radiolabelled urate uptake and efflux measurements. Membrane protein expression levels were determined by Biotinylation and Western Blot analysis. Results:Urate trans‐stimulated urate flux and efflux in wild type hSLC2A9a and 9b and most of their mutants, except S9A and W110A in the predicted N‐terminal phosphorylation site and TM7 of 9a, respectively. This result suggests that substitution of alanine at S9 and W110, removes the asymmetry of the transporter, which normally allows for trans‐acceleration. These finding advance our understanding of how trans‐stimulation contributes to the regulation of urate and hexoses by hSLC2A9. Grant Funding Source : CIHR