Publication: The SLC14 gene family of urea transporters
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Issued Date
2004-02-01
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ISSN
00316768
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2-s2.0-1242317687
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Mahidol University
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SCOPUS
Bibliographic Citation
Pflugers Archiv European Journal of Physiology. Vol.447, No.5 (2004), 603-609
Suggested Citation
Chairat Shayakul, Matthias A. Hediger The SLC14 gene family of urea transporters. Pflugers Archiv European Journal of Physiology. Vol.447, No.5 (2004), 603-609. doi:10.1007/s00424-003-1124-x Retrieved from: https://repository.li.mahidol.ac.th/handle/123456789/21229
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Title
The SLC14 gene family of urea transporters
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Abstract
Carrier-mediated urea transport allows rapid urea movement across the cell membrane, which is particularly important in the process of urinary concentration and for rapid urea equilibrium in non-renal tissues. Urea transporters mediate passive urea uptake that is inhibited by phloretin and urea analogues. Facilitated urea transporters are divided into two classes: (1) the renal tubular/testicular type of urea transporter, UT-A1 to -A5, encoded by alternative splicing of the SLC14A2 gene, and (2) the erythrocyte urea transporter UT-B1 encoded by the SLC14A1 gene. The primary structure of urea transporters is unique, consisting of two extended, hydrophobic, membrane-spanning domains and an extracellular glycosylated-connecting loop. UT-A1 is the result of a gene duplication of this two-halves-structure, and the duplicated portions are linked together by a large intracellular hydrophilic loop, carrying several putative protein kinase A (PKA) and -C (PKC) phosphorylation sites. UT-A1 is located in the apical membrane of the kidney inner medullary collecting duct cells, where it is stimulated acutely by cAMP-mediated phosphorylation in response to the antidiuretic hormone vasopressin. Vasopressin also up-regulates UT-A2 mRNA/protein expression in the descending thin limb of the loops of Henle. UT-A1 and UT-A2 are regulated independently and respond differently to changes in dietary protein content. UT-A3 and UT-A4 are located in the rat kidney medulla and UT-A5 in the mouse testis. The widely expressed UT-B participates in urea recycling in the descending vasa recta, as demonstrated by a relatively mild "urea- selective" urinary concentrating defect in transgenic UT-B null mice and individuals with the Jknull blood group.