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XB-ART-45029
FASEB J 2011 Dec 01;2512:4531-9. doi: 10.1096/fj.11-185991.
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Mature N-linked glycans facilitate UT-A1 urea transporter lipid raft compartmentalization.

Chen G , Howe AG , Xu G , Fröhlich O , Klein JD , Sands JM .


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The UT-A1 urea transporter is a glycoprotein with two different glycosylated forms of 97 and 117 kDa. In this study, we found the 117-kDa UT-A1 preferentially resides in lipid rafts, suggesting that the glycosylation status may interfere with UT-A1 lipid raft trafficking. This was confirmed by a site-directed mutagenesis study in MDCK cells. The nonglycosylated UT-A1 showed reduced localization in lipid rafts. By using sugar-specific binding lectins, we further found that the UT-A1 in nonlipid rafts contained a high amount of mannose, as detected by concanavalin A, while the UT-A1 in lipid rafts was the mature N-acetylglucosamine-containing form, as detected by wheat germ agglutinin. In the inner medulla (IM) of diabetic rats, the more abundant 117-kDa UT-A1 in lipid rafts was the mature glycosylation form, with high amounts of N-acetylglucosamine and sialic acid. In contrast, in the IM of normal rats, the predominant 97-kDa UT-A1 was the form enriched in mannose. Functionally, inhibition of glycosylation by tunicamycin or elimination of the glycosylation sites by mutation significantly reduced UT-A1 activity in oocytes. Taken together, our study reveals a new role of N-linked glycosylation in regulating UT-A1 activity by promoting UT-A1 trafficking into membrane lipid raft subdomains.

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Species referenced: Xenopus
Genes referenced: slc14a2

References [+] :
Blount, Phosphorylation of UT-A1 urea transporter at serines 486 and 499 is important for vasopressin-regulated activity and membrane accumulation. 2008, Pubmed