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Mature N ‐linked glycans facilitate UT‐A1 urea transporter lipid raft compartmentalization
Author(s) -
Chen Guangping,
Howe Ashley G.,
Xu Gang,
Fröhlich Otto,
Klein Janet D.,
Sands Jeff M.
Publication year - 2011
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/fj.11-185991
Subject(s) - lipid raft , glycosylation , wheat germ agglutinin , biochemistry , mannose , chemistry , glycoprotein , tunicamycin , glycan , concanavalin a , compartmentalization (fire protection) , raft , n linked glycosylation , microbiology and biotechnology , biology , lectin , membrane , endoplasmic reticulum , enzyme , organic chemistry , copolymer , in vitro , polymer , unfolded protein response
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.—Chen, G., Howe, A. G., Xu, G., Fröhlich, O., Klein, J. D., Sands, J. M. Mature N ‐linked glycans facilitate UT‐A1 urea transporter lipid raft compartmentalization. FASEB J. 25, 4531–4539 (2011). www.fasebj.org