N-Glycosylation is required for Na+-dependent vitamin C transporter functionality. Biochem Biophys Res Commun 2008 Sep 12;374(1):123-7
Date
07/16/2008Pubmed ID
18619416Pubmed Central ID
PMC2528843DOI
10.1016/j.bbrc.2008.06.120Scopus ID
2-s2.0-47749122550 (requires institutional sign-in at Scopus site) 46 CitationsAbstract
The human sodium-dependent vitamin C transporters (hSVCT1 and hSVCT2) mediate cellular uptake of ascorbic acid. Both these transporters contain potential sites for N-glycosylation in their extracellular domains (Asn-138, Asn-144 [hSVCT1]; Asn-188, Asn-196 [hSVCT2]), however the role of N-glycosylation in transporter function is unexplored. On the basis of the result that tunicamycin decreased (14)C-ascorbic acid uptake in HepG2 cells, we systematically ablated all consensus N-glycosylation sites in hSVCT1 and hSVCT2 to resolve any effects on ascorbic acid uptake, transporter expression and targeting. We show that removal of individual N-glycosylation sites significantly impairs protein expression and consequently ascorbic acid uptake for hSVCT1 mutants (N138Q is retained intracellularly) and for hSVCT2 mutants (all of which reach the cell surface). N-Glycosylation is therefore essential for vitamin C transporter functionality.
Author List
Subramanian VS, Marchant JS, Reidling JC, Said HMAuthor
Jonathan S. Marchant PhD Chair, Professor in the Cell Biology, Neurobiology and Anatomy department at Medical College of WisconsinMESH terms used to index this publication - Major topics in bold
Ascorbic AcidBiological Transport
Cell Line
Cell Membrane
Glycosylation
Humans
Mutation
Organic Anion Transporters, Sodium-Dependent
Protein Structure, Secondary
Sodium-Coupled Vitamin C Transporters
Symporters
Tunicamycin
