SLC5A9/SGLT4, a new Na+-dependent glucose transporter, is an essential transporter for mannose, 1,5-anhydro-D-glucitol, and fructose

Life Sci. 2005 Jan 14;76(9):1039-50. doi: 10.1016/j.lfs.2004.10.016.


We isolated a cDNA clone of SLC5A9/SGLT4 from human small intestinal full-length cDNA libraries, and functionally characterized it in vitro. The messenger RNA encoding SGLT4 was mainly expressed in the small intestine and kidney, among the human tissues tested. COS-7 cells transiently expressing SGLT4 exhibited Na(+)-dependent alpha-methyl-D-glucopyranoside (AMG) transport activity with an apparent K(m) of 2.6 mM, suggesting that SGLT4 is a low affinity-type transporter. The rank order of naturally occurring sugar analogs for the inhibition of AMG transport was: D-mannose (Man) >> D-glucose (Glc) > D-fructose (Fru) = 1,5-anhydro-D-glucitol (1,5AG) > D-galactose (Gal). Recognition of Man as a substrate was confirmed by direct uptake of Man into the cell. COS-7 cells expressing a putative murine SGLT4 ortholog showed similar Na(+)-dependent AMG transport activity and a similar deduced substrate specificity. These results suggest that SGLT4 would have unique physiological functions (i.e., absorption and/or reabsorption of Man, 1,5AG, and Fru, in addition to Glc).

MeSH terms

  • Amino Acid Sequence
  • Animals
  • COS Cells
  • Deoxyglucose / metabolism*
  • Fructose / metabolism*
  • Humans
  • Mannose / metabolism*
  • Molecular Sequence Data
  • Monosaccharide Transport Proteins / genetics
  • Monosaccharide Transport Proteins / physiology*
  • RNA, Messenger / analysis
  • Sodium-Glucose Transporter 2


  • Monosaccharide Transport Proteins
  • RNA, Messenger
  • SLC5A2 protein, human
  • Sodium-Glucose Transporter 2
  • Fructose
  • 1,5-anhydroglucitol
  • Deoxyglucose
  • Mannose