N-Glycosylation is required for Na+-dependent vitamin C transporter functionality

Veedamali S. Subramanian, Jonathan S. Marchant, Jack C. Reidling, Hamid M. Said

Research output: Contribution to journalArticle

33 Scopus citations

Abstract

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 14C-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.

Original languageEnglish (US)
Pages (from-to)123-127
Number of pages5
JournalBiochemical and Biophysical Research Communications
Volume374
Issue number1
DOIs
StatePublished - Sep 12 2008

Keywords

  • Ascorbic acid
  • Transport
  • hSVCT1
  • hSVCT2

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